Switch arrangements for ultrasonic surgical instruments

ABSTRACT

Ultrasonic surgical instruments including a handle housing, a switch frame, and a switch assembly are disclosed. The switch assembly may include a first switch arrangement movably supported on a distal portion of the handle housing and selectively movable relative to a first switch contact supported by the switch frame. The switch assembly may further include a second switch arrangement including a right switch button movably supported on a right side of the handle housing and selectively movable relative to a right switch contact supported by the switch frame, and a left switch button movably supported on a left side of the handle housing and selectively movable relative to a left switch contact supported by the switch frame. The first and second switch arrangements may be configured to be selectively actuatable by a single hand supporting the handle housing.

PRIORITY CLAIM

This application is a divisional application claiming priority under 35U.S.C. § 121 to U.S. patent application Ser. No. 15/260,882, entitledSWITCH ARRANGEMENTS FOR ULTRASONIC SURGICAL INSTRUMENTS, filed Sep. 9,2016, now U.S. Patent Application Publication No. 2016/0374709, which isa divisional application claiming priority under 35 U.S.C. § 121 to U.S.patent application Ser. No. 13/839,093, entitled SWITCH ARRANGEMENTS FORULTRASONIC SURGICAL INSTRUMENTS, filed Mar. 15, 2013, now U.S. Pat. No.9,439,668, which claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application Ser. No. 61/621,876, entitled DEVICES ANDTECHNIQUES FOR CUTTING AND COAGULATING TISSUE, filed Apr. 9, 2012, theentire disclosures of which are hereby incorporated by reference herein.

TECHNICAL FIELD

The present disclosure generally relates to ultrasonic surgical systemsand, more particularly, to ultrasonic and electrosurgical systems thatallows surgeons to perform cutting and coagulation.

BACKGROUND

Ultrasonic surgical instruments are finding increasingly widespreadapplications in surgical procedures by virtue of the unique performancecharacteristics of such instruments. Depending upon specific instrumentconfigurations and operational parameters, ultrasonic surgicalinstruments can provide substantially simultaneous cutting of tissue andhemostasis by coagulation, desirably minimizing patient trauma. Thecutting action is typically realized by an-end effector, or blade tip,at the distal end of the instrument, which transmits ultrasonic energyto tissue brought into contact with the end effector. Ultrasonicinstruments of this nature can be configured for open surgical use,laparoscopic, or endoscopic surgical procedures includingrobotic-assisted procedures.

Some surgical instruments utilize ultrasonic energy for both precisecutting and controlled coagulation. Ultrasonic energy cuts andcoagulates by using lower temperatures than those used byelectrosurgery. Vibrating at high frequencies (e.g., 55,500 times persecond), the ultrasonic blade denatures protein in the tissue to form asticky coagulum. Pressure exerted on tissue with the blade surfacecollapses blood vessels and allows the coagulum to form a hemostaticseal. The precision of cutting and coagulation is controlled by thesurgeon's technique and adjusting the power level, blade edge, tissuetraction, and blade pressure.

A primary challenge of ultrasonic technology for medical devices,however, continues to be sealing of blood vessels. Work done by theapplicant and others has shown that optimum vessel sealing occurs whenthe inner muscle layer of a vessel is separated and moved away from theadventitia layer prior to the application of standard ultrasonic energy.Current efforts to achieve this separation have involved increasing theclamp force applied to the vessel.

Furthermore, the user does not always have visual feedback of the tissuebeing cut. Accordingly, it would be desirable to provide some form offeedback to indicate to the user that the cut is complete when visualfeedback is unavailable. Moreover, without some form of feedbackindicator to indicate that the cut is complete, the user may continue toactivate the harmonic instrument even though the cut is complete, whichcause possible damage to the harmonic instrument and surrounding tissueby the heat that is generated when activating a harmonic instrument withlittle to nothing between the jaws.

The ultrasonic transducer may be modeled as an equivalent circuit havingfirst branch comprising a static capacitance and a second “motional”branch comprising a serially connected inductance, resistance andcapacitance that defines the electromechanical properties of theresonator. Conventional ultrasonic generators may include a tuninginductor for tuning out the static capacitance at a resonant frequencyso that substantially all of generator's current output flows into themotional branch. The motional branch current, along with the drivevoltage, define the impedance and phase magnitude. Accordingly, using atuning inductor, the generator's current output represents the motionalbranch current, and the generator is thus able to maintain its driveoutput at the ultrasonic transducer's resonant frequency. The tuninginductor also transforms the phase impedance plot of the ultrasonictransducer to improve the generator's frequency lock capabilities.However, the tuning inductor must be matched with the specific staticcapacitance of an ultrasonic transducer. A different ultrasonictransducer having a different static capacitance requires a differenttuning inductor.

Electrosurgical devices for applying electrical energy to tissue inorder to treat and/or destroy the tissue are also finding increasinglywidespread applications in surgical procedures. An electrosurgicaldevice typically includes a hand piece, an instrument having adistally-mounted end effector (e.g., one or more electrodes). The endeffector can be positioned against the tissue such that electricalcurrent is introduced into the tissue. Electrosurgical devices can beconfigured for bipolar or monopolar operation. During bipolar operation,current is introduced into and returned from the tissue by active andreturn electrodes, respectively, of the end effector. During monopolaroperation, current is introduced into the tissue by an active electrodeof the end effector and returned through a return electrode (e.g., agrounding pad) separately located on a patient's body. Heat generated bythe current flowing through the tissue may form hemostatic seals withinthe tissue and/or between tissues and thus may be particularly usefulfor sealing blood vessels, for example. The end effector of anelectrosurgical device may also include a cutting member that is movablerelative to the tissue and the electrodes to transect the tissue.

Electrical energy applied by an electrosurgical device can betransmitted to the instrument by a generator in communication with thehand piece. The electrical energy may be in the form of radio frequency(“RF”) energy. RF energy is a form of electrical energy that may be inthe frequency range of 300 kilohertz (kHz) to 1 megahertz (MHz). Inapplication, an electrosurgical device can transmit low frequency RFenergy through tissue, which causes ionic agitation, or friction, ineffect resistive heating, thereby increasing the temperature of thetissue. Because a sharp boundary is created between the affected tissueand the surrounding tissue, surgeons can operate with a high level ofprecision and control, without sacrificing un-targeted adjacent tissue.The low operating temperatures of RF energy is useful for removing,shrinking, or sculpting soft tissue while simultaneously sealing bloodvessels. RF energy works particularly well on connective tissue, whichis primarily comprised of collagen and shrinks when contacted by heat.

It would be desirable to provide a surgical instrument that overcomessome of the deficiencies of current instruments. The surgical systemdescribed herein overcomes those deficiencies.

FIGURES

The novel features of the described forms are set forth withparticularity in the appended claims. The described forms, however, bothas to organization and methods of operation, may be best understood byreference to the following description, taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a perspective view illustrating one form of an ultrasonicsurgical instrument.

FIG. 2 is an exploded perspective assembly view of one form of anultrasonic surgical instrument.

FIG. 3 is a schematic of one form of a clamp arm illustrating forcecalculations.

FIG. 4 is a graphical representation of current, voltage, power,impedance, and frequency waveforms of a conventional oscillator at highpower and lightly loaded.

FIG. 5 is a graphical representation of current, voltage, power,impedance, and frequency waveforms of a conventional oscillator at highpower and heavily loaded.

FIG. 6 is a graphical representation of a current step function waveformand voltage, power, impedance, and frequency waveforms of one form of anoscillator and unloaded.

FIG. 7 is a graphical representation of a current step function waveformand voltage, power, impedance, and frequency waveforms of one form of anoscillator and lightly loaded.

FIG. 8 is a graphical representation of a current step function waveformand voltage, power, impedance, and frequency waveforms of one form of anoscillator and heavily loaded.

FIG. 9 illustrates one form of a drive system of a generator, whichcreates the ultrasonic electrical signal for driving an ultrasonictransducer.

FIG. 10 illustrates one form of a surgical system comprising anultrasonic surgical instrument and a generator comprising a tissueimpedance module.

FIG. 11 illustrates one form of a drive system of a generator comprisinga tissue impedance module.

FIG. 12 illustrates one form of a clamp arm assembly that may beemployed with a surgical system.

FIG. 13 is a schematic diagram of a tissue impedance module coupled to ablade and a clamp arm assembly with tissue located there between.

FIG. 14 illustrates one form of a method for driving an end effectorcoupled to an ultrasonic drive system of a surgical instrument.

FIG. 15A illustrates a logic flow diagram of one form of determining achange in tissue state and activating an output indicator accordingly.

FIG. 15B is a logic flow diagram illustrating one form of the operationof the frequency inflection point analysis module.

FIG. 15C is a logic flow diagram 900 illustrating one form of theoperation of the voltage drop analysis module.

FIG. 16 illustrates one form of a surgical system comprising a generatorand various surgical instruments usable therewith.

FIG. 16A is a diagram of the ultrasonic surgical instrument of FIG. 16.

FIG. 17 is a diagram of the surgical system of FIG. 16.

FIG. 18 is a model illustrating motional branch current in one form.

FIG. 19 is a structural view of a generator architecture in one form.

FIG. 20 is a logic flow diagram of a tissue algorithm that may beimplemented in one form of a generator.

FIG. 21 is a logic flow diagram of a signal evaluation tissue algorithmportion of the tissue algorithm shown in FIG. 20 that may be implementedin one form of a generator.

FIG. 22 is a logic flow diagram for evaluating condition sets for thesignal evaluation tissue algorithm shown in FIG. 21 that may beimplemented in one form of a generator.

FIG. 23A is a graphical representation of frequency slope (first timederivative of frequency) versus time waveform of one form of a generatorduring a typical tissue cut.

FIG. 23B is a graphical representation of slope of frequency slope(second time derivative of frequency) versus time waveform shown indashed line superimposed over the waveform shown in FIG. 23A of one formof a generator during a typical tissue cut.

FIG. 24 is a graphical representation of frequency versus time waveformof one form of a generator during a typical tissue cut as it relates tothe graphical representation shown in FIG. 23A.

FIG. 25 is a graphical representation of drive power versus timewaveform of one form of a generator during a typical tissue cut as itrelates to the graphical representation shown in FIG. 23A.

FIG. 26 is a graphical representation of frequency slope versus timewaveform of one form of a generator during a burn-in test.

FIG. 27 is a graphical representation of frequency versus time waveformof one form of a generator during a burn-in test as it relates to thegraphical representation shown in FIG. 26.

FIG. 28 is a graphical representation of power consumption versus timewaveform of one form of a generator during a burn-in test as it relatesto the graphical representation shown in FIG. 26.

FIG. 29 is a graphical representation of frequency change over timewaveform of several generator/instrument combinations during burn-intests.

FIG. 30 is a graphical representation of normalized combined impedance,current, frequency, power, energy, and temperature waveforms of one formof a generator coupled to an ultrasonic instrument to make 10 successivecuts on excised porcine jejunum tissue as quickly as possible whilekeeping the generator running throughout.

FIG. 31A is a graphical representation of impedance and current versustime waveforms of one form of a generator during successive tissue cutsover a period of time.

FIG. 31B is a graphical representation of frequency versus time waveformof one form of a generator during successive tissue cuts over a periodof time.

FIG. 31C is a graphical representation of power, energy, and temperatureversus time waveforms of one form of a generator during successivetissue cuts over a period of time.

FIG. 32 is a combined graphical representation of frequency, weightedfrequency slope waveform calculated via exponentially weighted movingaverage with an alpha value of 0.1, and temperature versus time waveformof one form of a generator.

FIG. 33 is a graphical representation of a frequency versus timewaveform shown in FIG. 32.

FIG. 34 is a graphical representation of the weighted frequency slopeversus time waveform shown in FIG. 32.

FIG. 35 is a graphical representation of a frequency versus timewaveform of one form of a generator over ten cuts on jejunum tissue anda graphical representation of a temperature versus time signal.

FIG. 36 is a graphical representation of the frequency versus timewaveform shown in FIG. 35 of one form of a generator over ten cuts onjejunum tissue with activation of intervening tissue.

FIG. 37 is a graphical representation of a frequency slope versus timewaveform of one form of a generator over ten cuts on jejunum tissue.

FIG. 38 is a graphical representation of a power versus time waveformrepresentative of power consumed by a one form of a generator over tencuts on jejunum tissue.

FIG. 39 is a graphical representation of a current versus time waveformof one form of a generator over ten cuts on jejunum tissue.

FIG. 40 is a graphical representation of a “cross-back frequency slopethreshold” parameter in connection with a frequency slope vs. timewaveform of one form of a generator.

FIG. 41 is a combined graphical representation of a pulsed applicationof one form of an ultrasonic instrument on an excised carotid arteryshowing normalized power, current, energy, and frequency waveformsversus time.

FIG. 42A is a graphical representation of impedance and current versustime waveforms of one form of a generator during successive tissue cutsover a period of time.

FIG. 42B is a graphical representation of a frequency versus timewaveform of one form of a generator during successive tissue cuts over aperiod of time.

FIG. 42C is a graphical representation of power, energy, and temperatureversus time waveforms of one form of a generator during successivetissue cuts over a period of time.

FIG. 43 is a graphical representation of a calculated frequency slopewaveform for the pulsed application shown in FIG. 41 and FIGS. 50A-Cplotted on a gross scale.

FIG. 44 is a zoomed in view of the graphical representation of thecalculated frequency slope waveform for the pulsed application shown inFIG. 43.

FIG. 45 is a graphical representation of other data waveforms ofinterest such as impedance, power, energy, temperature.

FIG. 46 is a graphical representation of a summary of weighted frequencyslope versus power level for various ultrasonic instrument types.

FIG. 47 is a graphical representation of resonant frequency, averagedresonant frequency, and frequency slope versus time waveforms of oneform of a generator.

FIG. 48 is a zoomed in view of the resonant frequency and averagedresonant frequency versus time waveforms shown in FIG. 47.

FIG. 49 is a zoomed in view of the resonant frequency and current versustime waveforms of one form of a generator.

FIG. 50 is a graphical representation of normalized combined power,impedance, current, energy, frequency, and temperature waveforms of oneform of a generator coupled to an ultrasonic instrument.

FIGS. 51A and 51B are graphical representations of resonant frequencyand frequency slope, respectively, displayed by one form of anultrasonic instrument during an ultrasonic bite.

FIGS. 52A and 52B are graphical representations of resonant frequencyand frequency slope, respectively, displayed by one form of anultrasonic instrument during another ultrasonic tissue bite.

FIG. 53 is a logic flow diagram of one form of a tissue algorithmimplementing a baseline frequency cut-off condition that may beimplemented in one form of a generator to consider a baseline resonantfrequency of an ultrasonic blade.

FIGS. 54A and 54B are graphical representations of blade frequencydemonstrated in different example ultrasonic activations.

FIG. 55 is a graphical representation of resonant frequency andultrasonic impedance over time for one form including multiple cuts withan ultrasonic blade.

FIG. 56 is a logic flow diagram of a tissue algorithm that may beimplemented in one form of a generator and/or instrument to implement abaseline frequency cut-off condition in conjunction with otherconditions.

FIG. 57 is a logic flow diagram of one form of a signal evaluationtissue algorithm portion of the tissue algorithm shown in FIG. 20considering a baseline frequency cut-off condition.

FIG. 58 is a logic flow diagram of one form of a load monitoringalgorithm that may be implemented in one form of a generator.

FIG. 59 is a logic flow diagram for evaluating condition sets for thesignal evaluation tissue algorithm shown in FIG. 57 that may beimplemented in one form of a generator.

FIG. 60 is a logic flow diagram for implementing one form of theunfiltered condition set logic shown in FIG. 59 that may be implementedin one form of a generator.

FIG. 61 is a graphical representation of a frequency slope and a secondtime derivative of frequency illustrating a pair of load events.

FIG. 62 is a graphical representation of a frequency slope, a secondtime derivative of frequency, and a rolling delta demonstrating a loadevent.

FIG. 63 is graphical representation of another form of a frequencyslope, a second time derivative of frequency and a rolling deltademonstrating another load event.

FIG. 64 is a logic flow diagram for implementing one form of analgorithm applying a Condition Set including a load event trigger thatmay be implemented in one form of a generator.

FIG. 65 is a logic flow diagram for implementing one form of logic fordetermining whether a load condition exists in a surgical instrument.

FIG. 66 is a logic flow diagram of one form of a signal evaluationtissue algorithm portion of the tissue algorithm shown in FIG. 20considering a Condition Set utilizing a load event to arm Response Settriggers.

FIG. 67 is a logic flow diagram for evaluating condition sets for thesignal evaluation tissue algorithm shown in FIG. 66 that may beimplemented in one form of a generator.

FIG. 68 is a logic flow diagram of one form of a load monitoringalgorithm that may be implemented in one form of a generator, as shownin FIG. 67.

FIG. 69 is a logic flow diagram of one form of an unfiltered conditionset logic shown in FIG. 67 that may be implemented by one form of agenerator.

FIG. 70 is a chart illustrating a power or displacement plot for oneexample implementation of the algorithm of FIG. 71.

FIG. 71 is a logic flow diagram of one form of an algorithm for drivingan ultrasonic instrument sequentially at two power levels.

FIG. 72 is a chart illustrating burst pressures obtained with a surgicalinstrument operated according to the algorithm of FIG. 71 and operatedby activating the instrument at a single power level.

FIG. 73 is a chart illustrating transection times obtained for thetrials indicated in FIG. 72.

FIG. 74 is a chart illustrating a drive signal pattern according to oneform of the algorithm of FIG. 71.

FIG. 75 is a logic flow diagram of another form of the algorithm of FIG.71 implementing a rest time between a deactivation of the instrument anda subsequent activation.

FIG. 76 is a chart illustrating a drive signal pattern according to oneform of the algorithm of FIG. 75.

FIG. 77 is a logic flow diagram of another form of the algorithm of FIG.71 implementing a third drive signal.

FIG. 78 is a chart illustrating burst pressures obtained with a surgicalinstrument operated according to the algorithm of FIG. 71 versus thesurgical instrument operated according to the algorithm of FIG. 77.

FIG. 79 is a chart illustrating burst pressures obtained with a surgicalinstrument similar to the instrument operated according to the algorithmof FIG. 71 versus the surgical instrument operated according to thealgorithm of FIG. 78.

FIG. 80 is a chart illustrating transection times obtained for thetrials indicated in FIG. 79.

FIG. 81 is a logic flow diagram of one form of an algorithm implementingan initial clamping period.

FIG. 82 is a logic flow diagram of another form of an algorithmimplementing an initial clamping period.

FIG. 83 is a chart illustrating a drive signal pattern according to thealgorithm of FIG. 82.

FIG. 84 is a diagram showing an example neural network.

FIG. 85 is a plot of an example portion of an activation function forhidden neurons and/or output neuron(s) of a neural network.

FIG. 86 is a diagram indicating an example activation function forhidden neurons and/or output neuron(s) of a neural network.

FIG. 87 is a logic flow diagram of one form of an algorithm for traininga neural network, such as the neural network of FIG. 86, utilizingback-propagation.

FIG. 88 is a logic flow diagram of one form of an algorithm fordetecting a condition set for an ultrasonic instrument utilizing amulti-variable model.

FIG. 89 is a logic flow diagram showing one form of an algorithmutilizing a multi-variable model such as, for example, the neuralnetwork described herein.

FIG. 90 is a chart illustrating a drive signal pattern of oneimplementation of the algorithm of FIG. 89.

FIG. 91 is a chart illustrating a drive signal pattern of anotherimplementation of the algorithm of FIG. 89.

FIG. 92 is a logic flow diagram showing one form of an algorithm forutilizing a multi-variable model to monitor a condition set comprisingmultiple conditions.

FIG. 93 is a side view of one form of an ultrasonic surgical instrumentconfiguration comprising a rotatable electrical connection according tovarious forms described herein.

FIG. 94 is a side view of the ultrasonic surgical instrumentconfiguration of FIG. 93 showing the handle assembly and hand pieceprior to insertion of the hand piece into the handle assembly accordingto various forms described herein.

FIG. 95 illustrates a cross-section of a handle assembly of anultrasonic surgical instrument comprising a rotatable electricalconnection according to various forms described herein.

FIG. 96 is a perspective view of a connector module of an ultrasonicsurgical instrument coupled to a flex circuit and a hand piece accordingto various forms describe herein.

FIG. 97 is an exploded view of the connector module shown in FIG. 96according to various forms described herein.

FIG. 98 is a perspective view of an arrangement of inner and outer ringsand corresponding links of a connector module according to various formsdescribed herein.

FIG. 99 is a perspective view of a first ring conductor and a secondring conductor positioned in a housing of a connector module accordingto various forms described herein.

FIG. 100 is a perspective view of a distal side of a rotation couplinghaving inner and outer ring conductors and corresponding linkspositioned within recessed portions of the rotation coupling accordingto various forms described herein.

FIG. 101 is a perspective view of a connector module coupled to a distalend of a hand piece according to various forms described herein.

FIG. 102 is a proximal view of inner and outer ring conductors andcorresponding links positioned in a rotation coupling according tovarious forms described herein.

FIG. 103 is a perspective view of a distal side of a rotation couplinghaving inner and outer ring conductors and corresponding linkspositioned within recessed portions of the rotation coupling accordingto various forms described herein.

FIG. 104 is a left side elevational view of an ultrasonic handleassembly according to various forms described herein.

FIG. 105 is another left side view of the ultrasonic handle assembly ofFIG. 104 with a left handle housing segment removed according to variousforms described herein.

FIG. 106 is a side elevational view of a switch assembly for anultrasonic surgical instrument according to various forms describedherein.

FIG. 107 is a front view of the switch assembly of FIG. 106 according tovarious forms described herein.

FIG. 108 is a bottom view of the switch assembly of FIGS. 106 and 107according to various forms described herein.

FIG. 109 is a top view of the switch assembly of FIGS. 106-109 accordingto various forms herein.

FIG. 109A is a left side view of a portion of another ultrasonic handleassembly according to various forms described herein.

FIG. 110 is a left side elevational view of another ultrasonic handleassembly according to various forms described herein.

FIG. 111 is a right side elevational view of the ultrasonic handleassembly of FIG. 110 according to various forms described herein.

FIG. 112 is a perspective view of a portion of another ultrasonic handleassembly according to various forms described herein.

FIG. 113 is a perspective view of another second switch arrangementaccording to various forms described herein.

FIG. 114 is a rear elevational view of the second switch arrangement ofFIG. 113 according to various forms described herein.

FIG. 115 is a rear elevational view of another second switch arrangementaccording to various forms described herein.

FIG. 116 is a top view of a portion of a second switch arrangement andhandle assembly according to various forms describe herein.

FIG. 117 is a diagrammatic depiction of a switch assembly that may beemployed in connection with the various ultrasonic handle assembliesaccording to various forms described herein.

FIG. 118 is another diagrammatic depiction of the switch assembly ofFIG. 117 in an actuated position wherein a central switch has beenactuated according to various forms described herein.

FIG. 119 is another diagrammatic depiction of the switch assembly ofFIGS. 117 and 118 in another actuated position wherein a right switchhas been actuated according to various forms described herein.

FIG. 120 is another diagrammatic depiction of the switch assembly ofFIGS. 117-119 in another actuated position wherein a left switch hasbeen actuated according to various forms described herein.

FIG. 121 illustrates a block diagram of a system depicting a generatorcoupled to a medical instrument and a circuit.

FIG. 122 illustrates a block diagram of a circuit within an instrument.

FIG. 123 illustrates a timing diagram of current pulses in atransmission frame of a serial protocol at a generator output.

FIG. 124 illustrates a timing diagram of voltage pulses in atransmission frame of a serial protocol at a circuit output.

FIG. 125A illustrates a partial timing diagram of a serial protocol.

FIG. 125B illustrates a partial timing diagram of a serial protocol.

FIG. 125C illustrates a partial timing diagram of a serial protocol.

FIG. 125D illustrates a partial timing diagram of a serial protocol.

FIG. 126 illustrates one example timing diagram of a serial protocol.

FIG. 127 illustrates one example timing diagram of a serial protocol.

FIG. 128 illustrates example timing diagrams of a serial protocol.

DESCRIPTION

Applicant of the present application also owns the following patentapplications that were filed on Mar. 15, 2013 and which are each hereinincorporated by reference in their respective entireties:

U.S. patent application Ser. No. 13/839,014, entitled “DEVICES ANDTECHNIQUES FOR CUTTING AND COAGULATING TISSUE,” now U.S. Pat. No.9,237,921;

U.S. patent application Ser. No. 13/839,242, entitled “ROTATABLEELECTRICAL CONNECTION FOR ULTRASONIC SURGICAL INSTRUMENTS,” now U.S.Pat. No. 9,241,731;

U.S. patent application Ser. No. 13/839,351, entitled “SERIALCOMMUNICATION PROTOCOL FOR MEDICAL DEVICE,” now U.S. Pat. No. 9,226,766;and

U.S. patent application Ser. No. 13/839,470, entitled “TECHNIQUES FORCUTTING AND COAGULATING TISSUE FOR ULTRASONIC SURGICAL INSTRUMENTS,” nowU.S. Patent Application Publication No. 2013/0296908.

Before explaining various forms of ultrasonic surgical instruments indetail, it should be noted that the illustrative forms are not limitedin application or use to the details of construction and arrangement ofparts illustrated in the accompanying drawings and description. Theillustrative forms may be implemented or incorporated in other forms,variations and modifications, and may be practiced or carried out invarious ways. Further, unless otherwise indicated, the terms andexpressions employed herein have been chosen for the purpose ofdescribing the illustrative forms for the convenience of the reader andare not for the purpose of limitation thereof.

Further, it is understood that any one or more of thefollowing-described forms, expressions of forms, examples, can becombined with any one or more of the other following-described forms,expressions of forms, and examples.

Various forms are directed to improved ultrasonic surgical instrumentsconfigured for effecting tissue dissecting, cutting, and/or coagulationduring surgical procedures. In one form, an ultrasonic surgicalinstrument apparatus is configured for use in open surgical procedures,but has applications in other types of surgery, such as laparoscopic,endoscopic, and robotic-assisted procedures. Versatile use isfacilitated by selective use of ultrasonic energy.

The various forms will be described in combination with an ultrasonicinstrument as described herein. Such description is provided by way ofexample, and not limitation, and is not intended to limit the scope andapplications thereof. For example, any one of the described forms isuseful in combination with a multitude of ultrasonic instrumentsincluding those described in, for example, U.S. Pat. Nos. 5,938,633;5,935,144; 5,944,737; 5,322,055; 5,630,420; and 5,449,370.

As will become apparent from the following description, it iscontemplated that forms of the surgical instrument described herein maybe used in association with an oscillator unit of a surgical system,whereby ultrasonic energy from the oscillator unit provides the desiredultrasonic actuation for the present surgical instrument. It is alsocontemplated that forms of the surgical instrument described herein maybe used in association with a signal generator unit of a surgicalsystem, whereby electrical energy in the form of radio frequencies (RF),for example, is used to provide feedback to the user regarding thesurgical instrument. The ultrasonic oscillator and/or the signalgenerator unit may be non-detachably integrated with the surgicalinstrument or may be provided as separate components, which can beelectrically attachable to the surgical instrument.

One form of the present surgical apparatus is particularly configuredfor disposable use by virtue of its straightforward construction.However, it is also contemplated that other forms of the presentsurgical instrument can be configured for non-disposable or multipleuses. Detachable connection of the present surgical instrument with anassociated oscillator and signal generator unit is presently disclosedfor single-patient use for illustrative purposes only. However,non-detachable integrated connection of the present surgical instrumentwith an associated oscillator and/or signal generator unit is alsocontemplated. Accordingly, various forms of the presently describedsurgical instruments may be configured for single use and/or multipleuse with either detachable and/or non-detachable integral oscillatorand/or signal generator unit, without limitation, and all combinationsof such configurations are contemplated to be within the scope of thepresent disclosure.

With reference to FIGS. 1-3, one form of a surgical system 19 includingan ultrasonic surgical instrument 100 is illustrated. The surgicalsystem 19 includes an ultrasonic generator 30 connected to an ultrasonictransducer 50 via a suitable transmission medium such as a cable 22, andan ultrasonic surgical instrument 100. Although in the presentlydisclosed form, the generator 30 is shown separate from the surgicalinstrument 100, in one form, the generator 30 may be formed integrallywith the surgical instrument 100 to form a unitary surgical system 19.The generator 30 comprises an input device 406 located on a front panelof the generator 30 console. The input device 406 may comprise anysuitable device that generates signals suitable for programming theoperation of the generator 30 as subsequently described with referenceto FIG. 9. Still with reference to FIGS. 1-3, the cable 22 may comprisemultiple electrical conductors for the application of electrical energyto positive (+) and negative (−) electrodes of the ultrasonic transducer50. It will be noted that, in some applications, the ultrasonictransducer 50 may be referred to as a “hand piece” or “handle assembly”because the surgical instrument 100 of the surgical system 19 may beconfigured such that a surgeon may grasp and manipulate the ultrasonictransducer 50 during various procedures and operations. A suitablegenerator 30 is the GEN 300 available from Ethicon Endo-Surgery, Inc. ofCincinnati, Ohio as is disclosed in one or more of the following U.S.patents, all of which are incorporated by reference herein: U.S. Pat.No. 6,480,796 (Method for Improving the Start Up of an Ultrasonic SystemUnder Zero Load Conditions); U.S. Pat. No. 6,537,291 (Method forDetecting a Loose Blade in a Handle Connected to an Ultrasonic SurgicalSystem); U.S. Pat. No. 6,626,926 (Method for Driving an UltrasonicSystem to Improve Acquisition of Blade Resonance Frequency at Startup);U.S. Pat. No. 6,633,234 (Method for Detecting Blade Breakage Using Rateand/or Impedance Information); U.S. Pat. No. 6,662,127 (Method forDetecting Presence of a Blade in an Ultrasonic System); U.S. Pat. No.6,678,621 (Output Displacement Control Using Phase Margin in anUltrasonic Surgical Handle); U.S. Pat. No. 6,679,899 (Method forDetecting Transverse Vibrations in an Ultrasonic Handle); U.S. Pat. No.6,908,472 (Apparatus and Method for Altering Generator Functions in anUltrasonic Surgical System); U.S. Pat. No. 6,977,495 (DetectionCircuitry for Surgical Hand piece System); U.S. Pat. No. 7,077,853(Method for Calculating Transducer Capacitance to Determine TransducerTemperature); U.S. Pat. No. 7,179,271 (Method for Driving an UltrasonicSystem to Improve Acquisition of Blade Resonance Frequency at Startup);and U.S. Pat. No. 7,273,483 (Apparatus and Method for Alerting GeneratorFunction in an Ultrasonic Surgical System).

In accordance with the described forms, the ultrasonic generator 30produces an electrical signal or drive signal of a particular voltage,current, and frequency, e.g., 55,500 cycles per second (Hz). Thegenerator is 30 connected by the cable 22 to the handle assembly 68,which contains piezoceramic elements forming the ultrasonic transducer50. In response to a switch 312 a on the handle assembly 68 or a footswitch 434 connected to the generator 30 by another cable the generatorsignal is applied to the transducer 50, which causes a longitudinalvibration of its elements. The transducer 50 is secured to the handleassembly 68 via a connector 300. When installed, the transducer 50 isacoustically coupled to the surgical blade 79 via a structure orwaveguide 80 (FIG. 2). The structure 80 and blade 79 are consequentlyvibrated at ultrasonic frequencies when the drive signal is applied tothe transducer 50. The structure 80 is designed to resonate at theselected frequency, thus amplifying the motion initiated by thetransducer 50. In one form, the generator 30 is configured to produce aparticular voltage, current, and/or frequency output signal that can bestepped with high resolution, accuracy, and repeatability.

Referring to FIG. 4, in current systems a conventional oscillator isactivated at time 0 resulting in current 300 rising to a desired setpoint of approximately 340 mA. At approximately 2 seconds a light loadis applied resulting in corresponding increases to voltage 310, power320, impedance 330, and changes in resonant frequency 340.

Referring to FIG. 5, in current systems a conventional oscillator isactivated at time 0 resulting in the current 300 rising to a desired setpoint of approximately 340 mA. At approximately 2 seconds an increasingload is applied resulting in corresponding increases to the voltage 310,power 320, impedance 330, and changes in resonant frequency 340. Atapproximately 7 seconds, the load has increased to the point that theoscillator enters into a flat power mode where further increases in loadmaintain the power at 35 W as long as the oscillator stays withinvoltage limits of the power supply. The current 300 and therefore,displacement, varies during flat power mode. At approximately 11.5seconds, the load is reduced to the point where the current 300 returnsto the desired set point of approximately 340 mA. The voltage 310, power320, impedance 330, and resonant frequency 340 vary with the load.

With reference now back to FIGS. 1-3, the handle assembly 68 may be amulti-piece assembly adapted to isolate the operator from the vibrationsof the acoustic assembly contained within the ultrasonic transducer 50.The handle assembly 68 can be shaped to be held by a user in aconventional manner, but it is contemplated that the present ultrasonicsurgical instrument 100 principally be grasped and manipulated by atrigger-like arrangement provided by a handle assembly of theinstrument, as will be described. While a multi-piece handle assembly 68is illustrated, the handle assembly 68 may comprise a single or unitarycomponent. The proximal end of the ultrasonic surgical instrument 100receives and is fitted to the distal end of the ultrasonic transducer 50by insertion of the transducer 50 into the handle assembly 68. In oneform, the ultrasonic surgical instrument 100 may be attached to andremoved from the ultrasonic transducer 50 as a unit. In other forms, theultrasonic surgical instrument 100 and the ultrasonic transducer 50 maybe formed as an integral unit. The ultrasonic surgical instrument 100may include a handle assembly 68, comprising a mating housing portion69, a housing portion 70, and a transmission assembly 71. When thepresent instrument is configured for endoscopic use, the constructioncan be dimensioned such that the transmission assembly 71 has an outsidediameter of approximately 5.5 mm. The elongated transmission assembly 71of the ultrasonic surgical instrument 100 extends orthogonally from theinstrument handle assembly 68. The transmission assembly 71 can beselectively rotated with respect to the handle assembly 68 by a rotationknob 29 as further described below. The handle assembly 68 may beconstructed from a durable plastic, such as polycarbonate or a liquidcrystal polymer. It is also contemplated that the handle assembly 68 mayalternatively be made from a variety of materials including otherplastics, ceramics, or metals.

The transmission assembly 71 may include an outer tubular member or anouter sheath 72, an inner tubular actuating member 76, a waveguide 80,and an end effector 81 comprising, for example, the blade 79, a clamparm 56, and one or more clamp pads 58. The transducer 50 andtransmission assembly 71 (including or excluding the end effector 81)may be referred to as an ultrasonic drive system. As subsequentlydescribed, the outer sheath 72, the actuating member 76, and thewaveguide 80 or transmission rod may be joined together for rotation asa unit (together with the ultrasonic transducer 50) relative to thehandle assembly 68. The waveguide 80, which is adapted to transmitultrasonic energy from the ultrasonic transducer 50 to the blade 79 maybe flexible, semi-flexible, or rigid. The waveguide 80 also may beconfigured to amplify the mechanical vibrations transmitted through thewaveguide 80 to the blade 79 as is well known in the art. The waveguide80 may further have features to control the gain of the longitudinalvibration along the waveguide 80 and features to tune the waveguide 80to the resonant frequency of the system. In particular, the waveguide 80may have any suitable cross-sectional dimension. For example, thewaveguide 80 may have a substantially uniform cross-section or thewaveguide 80 may be tapered at various sections or may be tapered alongits entire length. In one expression of the current form, the waveguidediameter is about 0.113 inches nominal to minimize the amount ofdeflection at the blade 79 so that gapping in the proximal portion ofthe end effector 81 is minimized.

The blade 79 may be integral with the waveguide 80 and formed as asingle unit. In an alternate expression of the current form, the blade79 may be connected by a threaded connection, a welded joint, or othercoupling mechanisms. The distal end of the blade 79 is disposed near ananti-node in order to tune the acoustic assembly to a preferred resonantfrequency f_(o) when the acoustic assembly is not loaded by tissue. Whenthe ultrasonic transducer 50 is energized, the distal end of the blade79 is configured to move longitudinally in the range of, for example,approximately 10 to 500 microns peak-to-peak, and preferably in therange of about 20 to about 200 microns at a predetermined vibrationfrequency f_(o) of, for example, 55,500 Hz.

With particular reference to FIGS. 1-3, therein is illustrated one formof the clamp member 60 for use with the present ultrasonic surgicalinstrument 100 and which is configured for cooperative action with theblade 79. The clamp member 60 in combination with the blade 79 iscommonly referred to as the end effector 81, and the clamp member 60 isalso commonly referred to as the jaw. The clamp member 60 includes apivotally movable clamp arm 56, which is connected to the distal end ofthe outer sheath 72 and the actuating member 76, in combination with atissue engaging pad or clamp pad 58. The clamp arm 56 is pivotallymovable by a trigger 34 and the end effector 81 is rotatably movable bythe rotation knob 29. For example, the trigger 34 may be translatable bythe hand of the clinician in a proximal direction. For example, thehandle 34 may pivot about the pivot pin 36. Proximal motion or pivotingof the trigger 34 may cause distal motion of a yoke 301 mechanicallycoupled to the tubular actuating member 76. Distal motion of the tubularactuating member may cause the clamp arm 56 to pivot to close againstthe blade 79. Additional details of closure mechanisms for ultrasonicsurgical devices are provided herein below with respect to FIGS. 93-95and in U.S. patent application Ser. Nos. 12/503,769, 12/503,770, and12/503,766, each of which is incorporated herein by reference in itsentirety.

In one expression of the form, the clamp pad 58 is formed from TEFLON® atrademark name of E. I. Du Pont de Nemours and Company, a lowcoefficient of friction polymer material, or any other suitablelow-friction material. The clamp pad 58 mounts on the clamp arm 56 forcooperation with the blade 79, with pivotal movement of the clamp arm 56positioning the clamp pad 58 in substantially parallel relationship to,and in contact with, the blade 79, thereby defining a tissue treatmentregion. By this construction, tissue is grasped between the clamp pad 58and the blade 79. As illustrated, the clamp pad 58 may be provided witha non-smooth surface, such as a saw tooth-like configuration to enhancethe gripping of tissue in cooperation with the blade 79. The sawtooth-like configuration, or teeth, provide traction against themovement of the blade 79. The teeth also provide counter traction to theblade 79 and clamping movement. As would be appreciated by one skilledin the art, the saw tooth-like configuration is just one example of manytissue engaging surfaces to prevent movement of the tissue relative tothe movement of the blade 79. Other illustrative examples include bumps,criss-cross patterns, tread patterns, a bead, or sand blasted surface.

Due to sinusoidal motion, the greatest displacement or amplitude ofmotion is located at the most distal portion of the blade 79, while theproximal portion of the tissue treatment region is on the order of 50%of the distal tip amplitude. During operation, the tissue in theproximal region of the end effector 81 will desiccate and thin, and thedistal portion of the end effector 81 will transect tissue in thatdistal region, thereby allowing the desiccated and thinned tissue withinthe proximal region to slide distally into the more active region of theend effector 81 to complete the tissue transection.

FIG. 3 illustrates a force diagram and the relationship between theactuation force F_(A) (provided by the actuating member 76) andtransection force F_(T) (measured at the midpoint of the optimal tissuetreatment area).F _(T) =F _(A)(X ₂ /X ₁)  (1)

Where F_(A) equals the spring preload of a proximal spring 94 (lessfrictional losses), which, in one form, is about 12.5 pounds, and F_(T)equals about 4.5 pounds.

F_(T) is measured in the region of the clamp arm/blade interface whereoptimal tissue treatment occurs as defined by tissue marks 61 a and 61b. The tissue marks 61 a, b are etched or raised on the clamp arm 56 toprovide a visible mark to the surgeon so the surgeon has a clearindication of the optimal tissue treatment area. The tissue marks 61 a,b are about 7 mm apart in distance, and more preferably about 5 mm apartin distance.

FIG. 9 illustrates one form of a drive system 32 of the generator 30,which creates an ultrasonic electrical signal for driving an ultrasonictransducer, also referred to as a drive signal. The drive system 32 isflexible and can create an ultrasonic electrical drive signal 416 at adesired frequency and power level setting for driving the ultrasonictransducer 50. In various forms, the generator 30 may comprise severalseparate functional elements, such as modules and/or blocks. Althoughcertain modules and/or blocks may be described by way of example, it canbe appreciated that a greater or lesser number of modules and/or blocksmay be used and still fall within the scope of the forms. Further,although various forms may be described in terms of modules and/orblocks to facilitate description, such modules and/or blocks may beimplemented by one or more hardware components, e.g., processors,Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs),Application Specific Integrated Circuits (ASICs), circuits, registersand/or software components, e.g., programs, subroutines, logic and/orcombinations of hardware and software components.

In one form, the generator 30 drive system 32 may comprise one or moreembedded applications implemented as firmware, software, hardware, orany combination thereof. The generator 30 drive system 32 may comprisevarious executable modules such as software, programs, data, drivers,application program interfaces (APIs), and so forth. The firmware may bestored in nonvolatile memory (NVM), such as in bit-masked read-onlymemory (ROM) or flash memory. In various implementations, storing thefirmware in ROM may preserve flash memory. The NVM may comprise othertypes of memory including, for example, programmable ROM (PROM),erasable programmable ROM (EPROM), electrically erasable programmableROM (EEPROM), or battery backed random-access memory (RAM) such asdynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronousDRAM (SDRAM).

In one form, the generator 30 drive system 32 comprises a hardwarecomponent implemented as a processor 400 for executing programinstructions for monitoring various measurable characteristics of theultrasonic surgical instrument 100 (FIG. 1) and generating a stepfunction output signal for driving the ultrasonic transducer 50 incutting and/or coagulation operating modes. It will be appreciated bythose skilled in the art that the generator 30 and the drive system 32may comprise additional or fewer components and only a simplifiedversion of the generator 30 and the drive system 32 are described hereinfor conciseness and clarity. In various forms, as previously discussed,the hardware component may be implemented as a DSP, PLD, ASIC, circuits,and/or registers. In one form, the processor 400 may be configured tostore and execute computer software program instructions to generate thestep function output signals for driving various components of theultrasonic surgical instrument 100, such as the transducer 50, the endeffector 81, and/or the blade 79.

In one form, under control of one or more software program routines, theprocessor 400 executes the methods in accordance with the describedforms to generate a step function formed by a stepwise waveform of drivesignals comprising current (I), voltage (V), and/or frequency (f) forvarious time intervals or periods (T). The stepwise waveforms of thedrive signals may be generated by forming a piecewise linear combinationof constant functions over a plurality of time intervals created bystepping the generator 30 drive signals, e.g., output drive current (I),voltage (V), and/or frequency (f). The time intervals or periods (T) maybe predetermined (e.g., fixed and/or programmed by the user) or may bevariable. Variable time intervals may be defined by setting the drivesignal to a first value and maintaining the drive signal at that valueuntil a change is detected in a monitored characteristic. Examples ofmonitored characteristics may comprise, for example, transducerimpedance, tissue impedance, tissue heating, tissue transection, tissuecoagulation, and the like. The ultrasonic drive signals generated by thegenerator 30 include, without limitation, ultrasonic drive signalscapable of exciting the ultrasonic transducer 50 in various vibratorymodes such as, for example, the primary longitudinal mode and harmonicsthereof as well flexural and torsional vibratory modes.

In one form, the executable modules comprise one or more step functionalgorithm(s) 402 stored in memory that when executed causes theprocessor 400 to generate a step function formed by a stepwise waveformof drive signals comprising current (I), voltage (V), and/or frequency(f) for various time intervals or periods (T). The stepwise waveforms ofthe drive signals may be generated by forming a piecewise linearcombination of constant functions over two or more time intervalscreated by stepping the generator's 30 output drive current (I), voltage(V), and/or frequency (f). The drive signals may be generated either forpredetermined fixed time intervals or periods (T) of time or variabletime intervals or periods of time in accordance with the one or morestepped output algorithm(s) 402. Under control of the processor 400, thegenerator 30 steps (e.g., increment or decrement) the current (I),voltage (V), and/or frequency (f) up or down at a particular resolutionfor a predetermined period (T) or until a predetermined condition isdetected, such as a change in a monitored characteristic (e.g.,transducer impedance, tissue impedance). The steps can change inprogrammed increments or decrements. If other steps are desired, thegenerator 30 can increase or decrease the step adaptively based onmeasured system characteristics.

In operation, the user can program the operation of the generator 30using the input device 406 located on the front panel of the generator30 console. The input device 406 may comprise any suitable device thatgenerates signals 408 that can be applied to the processor 400 tocontrol the operation of the generator 30. In various forms, the inputdevice 406 includes buttons, switches, thumbwheels, keyboard, keypad,touch screen monitor, pointing device, remote connection to a generalpurpose or dedicated computer. In other forms, the input device 406 maycomprise a suitable user interface. Accordingly, by way of the inputdevice 406, the user can set or program the current (I), voltage (V),frequency (f), and/or period (T) for programming the step functionoutput of the generator 30. The processor 400 then displays the selectedpower level by sending a signal on line 410 to an output indicator 412.

In various forms, the output indicator 412 may provide visual, audible,and/or tactile feedback to the surgeon to indicate the status of asurgical procedure, such as, for example, when tissue cutting andcoagulating is complete based on a measured characteristic of theultrasonic surgical instrument 100, e.g., transducer impedance, tissueimpedance, or other measurements as subsequently described. By way ofexample, and not limitation, visual feedback comprises any type ofvisual indication device including incandescent lamps or light emittingdiodes (LEDs), graphical user interface, display, analog indicator,digital indicator, bar graph display, digital alphanumeric display. Byway of example, and not limitation, audible feedback comprises any typeof buzzer, computer generated tone, computerized speech, voice userinterface (VUI) to interact with computers through a voice/speechplatform. By way of example, and not limitation, tactile feedbackcomprises any type of vibratory feedback provided through the instrumenthousing handle assembly 68.

In one form, the processor 400 may be configured or programmed togenerate a digital current signal 414 and a digital frequency signal418. These signals 414, 418 are applied to a direct digital synthesizer(DDS) circuit 420 to adjust the amplitude and the frequency (f) of thecurrent output signal 416 to the transducer 50. The output of the DDScircuit 420 is applied to an amplifier 422 whose output is applied to atransformer 424. The output of the transformer 424 is the signal 416applied to the ultrasonic transducer 50, which is coupled to the blade79 by way of the waveguide 80 (FIG. 2).

In one form, the generator 30 comprises one or more measurement modulesor components that may be configured to monitor measurablecharacteristics of the ultrasonic instrument 100 (FIG. 1). In theillustrated form, the processor 400 may be employed to monitor andcalculate system characteristics. As shown, the processor 400 measuresthe impedance Z of the transducer 50 by monitoring the current suppliedto the transducer 50 and the voltage applied to the transducer 50. Inone form, a current sense circuit 426 is employed to sense the currentflowing through the transducer 50 and a voltage sense circuit 428 isemployed to sense the output voltage applied to the transducer 50. Thesesignals may be applied to the analog-to-digital converter 432 (ADC) viaan analog multiplexer 430 circuit or switching circuit arrangement. Theanalog multiplexer 430 routes the appropriate analog signal to the ADC432 for conversion. In other forms, multiple ADCs 432 may be employedfor each measured characteristic instead of the multiplexer 430 circuit.The processor 400 receives the digital output 433 of the ADC 432 andcalculates the transducer impedance Z based on the measured values ofcurrent and voltage. The processor 400 adjusts the output drive signal416 such that it can generate a desired power versus load curve. Inaccordance with programmed step function algorithms 402, the processor400 can step the drive signal 416, e.g., the current or frequency, inany suitable increment or decrement in response to the transducerimpedance Z.

To actually cause the surgical blade 79 to vibrate, e.g., actuate theblade 79, the user activates the foot switch 434 (FIG. 1) or the switch312 a (FIG. 1) on the handle assembly 68. This activation outputs thedrive signal 416 to the transducer 50 based on programmed values ofcurrent (I), frequency (f), and corresponding time periods (T). After apredetermined fixed time period (T), or variable time period based on ameasurable system characteristic such as changes in the impedance Z ofthe transducer 50, the processor 400 changes the output current step orfrequency step in accordance with the programmed values. The outputindicator 412 communicates the particular state of the process to theuser.

The programmed operation of the generator 30 can be further illustratedwith reference to FIGS. 6, 7, and 8, where graphical representations ofcurrent 300, voltage 310, power 320, impedance 330, and frequency 340are shown for the generator 30 in an unloaded state, a lightly loadedstate, and a heavily loaded state, respectively. FIG. 6 is a graphicalrepresentation of current 300, voltage 310, power 320, impedance 330,and frequency 340 waveforms of one form of the generator 30 in anunloaded state. In the illustrated form, the current 300 output of thegenerator 30 is stepped. As shown in FIG. 6, the generator 30 isinitially activated at about time 0 resulting in the current 300 risingto a first set point I₁ of about 100 mA. The current 300 is maintainedat the first set point I₁, for a first period T₁. At the end of thefirst period T₁, e.g., about 1 second in the illustrated form, thecurrent 300 set point I₁ is changed, e.g., stepped, by the generator 30in accordance with the software, e.g., the step function algorithm(s)402, to a second set point I₂ of about 175 mA for a second period T₂,e.g., about 2 seconds in the illustrated form. At the end of the secondperiod T₂, e.g., at about 3 seconds in the illustrated form, thegenerator 30 software changes the current 300 to a third set point I₃ ofabout 350 mA. The voltage 310, current 300, power 320, and frequencyrespond only slightly because there is no load on the system.

FIG. 7 is a graphical representation of the current 300, voltage 310,power 320, impedance 330, and frequency 340 waveforms of one form of thegenerator 30 under a lightly loaded state. Referring to FIG. 7, thegenerator 30 is activated at about time 0 resulting in the current 300rising to the first current 300 set point I₁ of about 100 mA. At about 1second the current 300 set point is changed within the generator 30 bythe software to I₂ of about 175 mA, and then again at about 3 secondsthe generator 30 changes the current 300 set point to I₃ of about 350mA. The voltage 310, current 300, power 320, and frequency 340 are shownresponding to the light load similar to that shown in FIG. 4.

FIG. 8 is a graphical representation of the current 300, voltage 310,power 320, impedance 330, and frequency 340 waveforms of one form of thegenerator 30 under a heavily loaded state. Referring to FIG. 8, thegenerator 30 is activated at about time 0 resulting in the current 300rising to the first set point I₁ of about 100 mA. At about 1 second thecurrent 300 set point is changed within the generator 30 by the softwareto I₂ of about 175 mA, and then again at about 3 seconds the generator30 changes the current 300 set point to I₃ of about 350 mA. The voltage310, current 300, power 320, and frequency 340 are shown responding tothe heavy load similar to that shown in FIG. 5.

It will be appreciated by those skilled in the art that the current 300step function set points (e.g., I₁, I₂, I₃) and the time intervals orperiods (e.g., T₁, T₂) of duration for each of the step function setpoints described in FIGS. 6-8 are not limited to the values describedherein and may be adjusted to any suitable value as may be desired for agiven set of surgical procedures. Additional or fewer current set pointsand periods of duration may be selected as may be desired for a givenset of design characteristics or performance constraints. As previouslydiscussed, the periods may be predetermined by programming or may bevariable based on measurable system characteristics. The forms are notlimited in this context. For example, in certain forms, the amplitudes(set points) of consecutive pulses may increase, decrease or stay thesame. For example, in certain forms, the amplitudes of consecutivepulses may be equal. Also, in certain forms, the time intervals orperiods of the pulses may take any suitable value including, forexample, fractions of a second, minutes, hours, etc. In one exampleform, the time interval or periods of the pulses may be 55 seconds.

Having described operational details of various forms of the surgicalsystem 19, operations for the above surgical system 19 may be furtherdescribed in terms of a process for cutting and coagulating a bloodvessel employing a surgical instrument comprising the input device 406and the transducer impedance measurement capabilities described withreference to FIG. 9. Although a particular process is described inconnection with the operational details, it can be appreciated that theprocess merely provides an example of how the general functionalitydescribed herein can be implemented by the surgical system 19. Further,the given process does not necessarily have to be executed in the orderpresented herein unless otherwise indicated. As previously discussed,the input device 406 may be employed to program the stepped output(e.g., current, voltage, frequency) to the ultrasonic transducer50/blade 79 assembly.

Accordingly, with reference now to FIGS. 1-3 and 6-9, one technique forsealing a vessel includes separating and moving the inner muscle layerof the vessel away from the adventitia layer prior to the application ofstandard ultrasonic energy to transect and seal the vessel. Althoughconventional methods have achieved this separation by increasing theforce applied to the clamp member 60, disclosed is an alternativeapparatus and method for cutting and coagulating tissue without relyingon clamp force alone. In order to more effectively separate the tissuelayers of a vessel, for example, the generator 30 may be programmed toapply a frequency step function to the ultrasonic transducer 50 tomechanically displace the blade 79 in multiple modes in accordance withthe step function. In one form, the frequency step function may beprogrammed by way of the user interface 406, wherein the user can selecta stepped-frequency program, the frequency (f) for each step, and thecorresponding time period (T) of duration for each step for which theultrasonic transducer 50 will be excited. The user may program acomplete operational cycle by setting multiple frequencies for multipleperiods to perform various surgical procedures.

In certain forms, the amplitudes of consecutive steps or pulses mayincrease, decrease or stay the same. For example, in certain forms, theamplitudes of consecutive pulses may be equal. Also, in certain forms,the time periods of the pulses may take any suitable value including,for example, fractions of a second, minutes, hours, etc. In one exampleform, the time period of the pulses may be 55 seconds.

In one form, a first ultrasonic frequency may be set initially tomechanically separate the muscle tissue layer of a vessel prior toapplying a second ultrasonic frequency to cut and seal the vessel. Byway of example, and not limitation, in accordance with oneimplementation of the program, initially, the generator 30 is programmedto output a first drive frequency f₁ for a first period T₁ of time (forexample less than approximately 1 second), wherein the first frequencyf₁ is significantly off resonance, for example, f_(o)/2, 2f_(o) or otherstructural resonant frequencies, where f_(o) is the resonant frequency(e.g., 55.5 kHz). The first frequency f₁ provides a low level ofmechanical vibration action to the blade 79 that, in conjunction withthe clamp force, mechanically separates the muscle tissue layer(subtherapeutic) of the vessel without causing significant heating thatgenerally occurs at resonance. After the first period T₁, the generator30 is programmed to automatically switch the drive frequency to theresonant frequency f_(o) for a second period T₂ to transect and seal thevessel. The duration of the second period T₂ may be programmed or may bedetermined by the length of time it actually takes to cut and seal thevessel as determined by the user or may be based on measured systemcharacteristics such as the transducer impedance Z as described in moredetail below.

In one form, the tissue/vessel transection process (e.g., separating themuscle layer of the vessel from the adventitia layer andtransecting/sealing the vessel) may be automated by sensing theimpedance Z characteristics of the transducer 50 to detect when thetransection of the tissue/vessel occurs. The impedance Z can becorrelated to the transection of the muscle layer and to thetransection/sealing of the vessel to provide a trigger for the processor400 to generate the frequency and/or current step function output. Aspreviously discussed with reference to FIG. 9, the impedance Z of thetransducer 50 may be calculated by the processor 400 based on thecurrent flowing through transducer 50 and the voltage applied to thetransducer 50 while the blade 79 is under various loads. Because theimpedance Z of the transducer 50 is proportional to the load applied tothe blade 79, as the load on the blade 79 increases, the impedance Z ofthe transducer 50 increases, and as the load on the blade 79 decreasesthe impedance Z of the transducer 50 decreases. Accordingly, theimpedance Z of the transducer 50 can be monitored to detect thetransection of the inner muscle tissue layer of the vessel from theadventitia layer and can also be monitored to detect when the vessel hasbeen transected and sealed.

In one form, the ultrasonic surgical instrument 110 may be operated inaccordance with a programmed step function algorithm responsive to thetransducer impedance Z. In one form, a frequency step function outputmay be initiated based on a comparison of the transducer impedance Z andone or more predetermined thresholds that have been correlated withtissue loads against the blade 79. When the transducer impedance Ztransitions above or below (e.g., crosses) a threshold, the processor400 applies a digital frequency signal 418 to the DDS circuit 420 tochange the frequency of the drive signal 416 by a predetermined step inaccordance with the step function algorithm(s) 402 responsive to thetransducer impedance Z. In operation, the blade 79 is first located atthe tissue treatment site. The processor 400 applies a first digitalfrequency signal 418 to set a first drive frequency f1 that is offresonance (e.g., f_(o)/2, 2f_(o) or other structural resonantfrequencies, where f_(o) is the resonant frequency). The drive signal416 is applied to the transducer 50 in response to activation of theswitch 312 a on the handle assembly 68 or the foot switch 434. Duringthis period the ultrasonic transducer 50 mechanically activates theblade 79 at the first drive frequency f₁. A force or load may be appliedto the clamp member 60 and the blade 79 to facilitate this process.During this period, the processor 400 monitors the transducer impedanceZ until the load on the blade 79 changes and the transducer impedance Zcrosses a predetermined threshold to indicate that the tissue layer hasbeen transected. The processor 400 then applies a second digitalfrequency signal 418 to set a second drive frequency f₂, e.g., theresonant frequency f_(o) or other suitable frequency for transecting,coagulating, and sealing tissue. Another portion of the tissue (e.g.,the vessel) is then grasped between the clamp member 60 and the blade79. The transducer 50 is now energized by the drive signal 416 at thesecond drive frequency f₂ by actuating either the foot switch 434 or theswitch 312 a on the handle assembly 68. It will be appreciated by thoseskilled in the art that the drive current (I) output also may be steppedas described with reference to FIGS. 6-8 based on the transducerimpedance Z.

According to one step function algorithm 402, the processor 400initially sets a first drive frequency f₁ that is significantly offresonance to separate the inner muscle layer of the vessel from theadventitia layer. During this period of operation the processor 400monitors the transducer impedance Z to determine when the inner musclelayer is transected or separated from the adventitia layer. Because thetransducer impedance Z is correlated to the load applied to the blade79, for example, cutting more tissue decrease the load on the blade 79and the transducer impedance Z. The transection of the inner musclelayer is detected when the transducer impedance Z drops below apredetermined threshold. When the change in transducer impedance Zindicates that the vessel has been separated from the inner musclelayer, the processor 400 sets the drive frequency to the resonantfrequency f_(o). The vessel is then grasped between the blade 79 and theclamp member 60 and the transducer 50 is activated by actuating eitherthe foot switch or the switch on the handle assembly 68 to transect andseal the vessel. In one form, the impedance Z change may range betweenabout 1.5 to about 4 times a base impedance measurements from an initialpoint of contact with the tissue to a point just before the muscle layeris transected and sealed.

FIG. 10 illustrates one form of a surgical system 190 comprising anultrasonic surgical instrument 120 and a generator 500 comprising atissue impedance module 502. Although in the presently disclosed form,the generator 500 is shown separate from the surgical instrument 120, inone form, the generator 500 may be formed integrally with the surgicalinstrument 120 to form a unitary surgical system 190. In one form, thegenerator 500 may be configured to monitor the electrical impedance ofthe tissue Z_(t) and to control the characteristics of time and powerlevel based on the tissue impedance Z_(t). In one form, the tissueimpedance Z_(t) may be determined by applying a subtherapeutic radiofrequency (RF) signal to the tissue and measuring the current throughthe tissue by way of a return electrode on the clamp member 60. In theform illustrated in FIG. 10, an end effector 810 portion of the surgicalsystem 190 comprises a clamp arm assembly 451 connected to the distalend of the outer sheath 72. The blade 79 forms a first (e.g.,energizing) electrode and the clamp arm assembly 451 comprises anelectrically conductive portion that forms a second (e.g., return)electrode. The tissue impedance module 502 is coupled to the blade 79and the clamp arm assembly 451 through a suitable transmission mediumsuch as a cable 504. The cable 504 comprises multiple electricalconductors for applying a voltage to the tissue and providing a returnpath for current flowing through the tissue back to the impedance module502. In various forms, the tissue impedance module 502 may be formedintegrally with the generator 500 or may be provided as a separatecircuit coupled to the generator 500 (shown in phantom to illustratethis option). The generator 500 is substantially similar to thegenerator 30 with the added feature of the tissue impedance module 502.

FIG. 11 illustrates one form of a drive system 321 of the generator 500comprising the tissue impedance module 502. The drive system 321generates the ultrasonic electrical drive signal 416 to drive theultrasonic transducer 50. In one form, the tissue impedance module 502may be configured to measure the impedance Z_(t) of tissue graspedbetween the blade 79 and the clamp arm assembly 451. The tissueimpedance module 502 comprises an RF oscillator 506, a voltage sensingcircuit 508, and a current sensing circuit 510. The voltage and currentsensing circuits 508, 510 respond to the RF voltage v_(rf) applied tothe blade 79 electrode and the RF current i_(rf) flowing through theblade 79 electrode, the tissue, and the conductive portion of the clamparm assembly 451. The sensed voltage v_(rf) and current i_(rf) areconverted to digital form by the ADC 432 via the analog multiplexer 430.The processor 400 receives the digitized output 433 of the ADC 432 anddetermines the tissue impedance Z_(t) by calculating the ratio of the RFvoltage v_(rf) to current i_(rf) measured by the voltage sense circuit508 and the current sense circuit 510. In one form, the transection ofthe inner muscle layer and the tissue may be detected by sensing thetissue impedance Z_(t). Accordingly, detection of the tissue impedanceZ_(t) may be integrated with an automated process for separating theinner muscle layer from the outer adventitia layer prior to transectingthe tissue without causing a significant amount of heating, whichnormally occurs at resonance.

FIG. 12 illustrates one form of the clamp arm assembly 451 that may beemployed with the surgical system 190 (FIG. 10). In the illustratedform, the clamp arm assembly 451 comprises a conductive jacket 472mounted to a base 449. The conductive jacket 472 is the electricallyconductive portion of the clamp arm assembly 451 that forms the second,e.g., return, electrode. In one implementation, the clamp arm 56 (FIG.3) may form the base 449 on which the conductive jacket 472 is mounted.In various forms, the conductive jacket 472 may comprise a centerportion 473 and at least one downwardly-extending sidewall 474 which canextend below the bottom surface 475 of the base 449. In the illustratedform, the conductive jacket 472 has two sidewalls 474 extendingdownwardly on opposite sides of the base 449. In other forms, the centerportion 473 may comprise at least one aperture 476 which can beconfigured to receive a projection 477 extending from the base 449. Insuch forms, the projections 477 can be press-fit within the apertures476 in order to secure the conductive jacket 472 to the base 449. Inother forms, the projections 477 can be deformed after they are insertedinto the apertures 476. In various forms, fasteners can be used tosecure the conductive jacket 472 to the base 449.

In various forms, the clamp arm assembly 451 may comprise anon-electrically conductive or insulative material, such as plasticand/or rubber, for example, positioned intermediate the conductivejacket 472 and the base 449. The electrically insulative material canprevent current from flowing, or shorting, between the conductive jacket472 and the base 449. In various forms, the base 449 may comprise atleast one aperture 478, which can be configured to receive a pivot pin(not illustrated). The pivot pin can be configured to pivotably mountthe base 449 to the sheath 72 (FIG. 10), for example, such that theclamp arm assembly 451 can be rotated between open and closed positionsrelative to the sheath 72. In the illustrated form, the base 449includes two apertures 478 positioned on opposite sides of the base 449.In one form, a pivot pin may be formed of or may comprise anon-electrically conductive or insulative material, such as plasticand/or rubber, for example, which can be configured to prevent currentfrom flowing into the sheath 72 even if the base 449 is in electricalcontact with the conductive jacket 472, for example. Additional clamparm assemblies comprising various forms of electrodes may be employed.Examples of such clamp arm assemblies are described in commonly-ownedand U.S. patent application Ser. Nos. 12/503,769, 12/503,770, and12/503,766, each of which is incorporated herein by reference in itsentirety.

FIG. 13 is a schematic diagram of the tissue impedance module 502coupled to the blade 79 and the clamp arm assembly 415 with tissue 514located there between. With reference now to FIGS. 10-13, the generator500 comprises the tissue impedance module 502 configured for monitoringthe impedance of the tissue 514 (Z_(t)) located between the blade 79 andthe clamp arm assembly 451 during the tissue transection process. Thetissue impedance module 502 is coupled to the ultrasonic surgicalinstrument 120 by way of the cable 504. The cable 504 includes a first“energizing” conductor 504 a connected to the blade 79 (e.g., positive[+] electrode) and a second “return” conductor 504 b connected to theconductive jacket 472 (e.g., negative [−] electrode) of the clamp armassembly 451. In one form, RF voltage v_(rf) is applied to the blade 79to cause RF current i_(rf) to flow through the tissue 514. The secondconductor 504 b provides the return path for the current i_(rf) back tothe tissue impedance module 502. The distal end of the return conductor504 b is connected to the conductive jacket 472 such that the currenti_(rf) can flow from the blade 79, through the tissue 514 positionedintermediate the conductive jacket 472 and the blade 79, and theconductive jacket 472 to the return conductor 504 b. The impedancemodule 502 connects in circuit, by way of the first and secondconductors 504 a, b. In one form, the RF energy may be applied to theblade 79 through the ultrasonic transducer 50 and the waveguide 80 (FIG.2). It is worthwhile noting that the RF energy applied to the tissue 514for purposes of measuring the tissue impedance Z_(t) is a low levelsubtherapeutic signal that does not contribute in a significant manner,or at all, to the treatment of the tissue 514.

Having described operational details of various forms of the surgicalsystem 190, operations for the above surgical system 190 may be furtherdescribed with reference to FIGS. 10-13 in terms of a process forcutting and coagulating a blood vessel employing a surgical instrumentcomprising the input device 406 and the tissue impedance module 502.Although a particular process is described in connection with theoperational details, it can be appreciated that the process merelyprovides an example of how the general functionality described hereincan be implemented by the surgical system 190. Further, the givenprocess does not necessarily have to be executed in the order presentedherein unless otherwise indicated. As previously discussed, the inputdevice 406 may be employed to program the step function output (e.g.,current, voltage, frequency) to the ultrasonic transducer 50/blade 79assembly.

In one form, a first conductor or wire may be connected to the outersheath 72 of the instrument 120 and a second conductor or wire may beconnected to the blade 79/transducer 50. By nature of the design, theblade 79 and the transducer 50 are electrically isolated from the outersheath 72 as well as other elements of the actuation mechanism for theinstrument 120 including the base 449 and the inner sheath 76. The outersheath 79 and other elements of the actuation mechanism including thebase 449 and the inner sheath 76 are all electrically continuous withone another—that is, they are all metallic and touch one another.Accordingly, by connecting a first conductor to the outer sheath 72 andconnecting a second conductor to the blade 79 or the transducer 50 suchthat the tissue resides between these two conductive pathways, thesystem can monitor the electrical impedance of the tissue as long as thetissue contacts both the blade 79 and the base 449. To facilitate thiscontact, the base 449 itself may include outwardly and possiblydownwardly protruding features to assure tissue contact while,effectively integrating conductive jacket 472 into base 449.

In one form, the ultrasonic surgical instrument 120 may be operated inaccordance with a programmed step function algorithm 402 responsive tothe tissue impedance Z_(t). In one form, a frequency step functionoutput may be initiated based on a comparison of the tissue impedanceZ_(t) and predetermined thresholds that have been correlated withvarious tissue states (e.g., desiccation, transection, sealing). Whenthe tissue impedance Z_(t) transitions above or below (e.g., crosses) athreshold, the processor 400 applies a digital frequency signal 418 tothe DDS circuit 420 to change the frequency of an ultrasonic oscillatorby a predetermined step in accordance with the step function algorithm402 responsive to the tissue impedance Z_(t).

In operation, the blade 79 is located at the tissue treatment site. Thetissue 514 is grasped between the blade 79 and the clamp arm assembly451 such that the blade 79 and the conductive jacket 472 make electricalcontact with the tissue 514. The processor 400 applies a first digitalfrequency signal 418 to set a first drive frequency f₁ that is offresonance (e.g., f_(o)/2, 2f_(o) or other structural resonantfrequencies, where f_(o) is the resonant frequency). The blade 79 iselectrically energized by the low level subtherapeutic RF voltage v_(rf)supplied by the tissue impedance module 502. The drive signal 416 isapplied to the transducer 50/blade 79 in response to actuation of theswitch 312 a on the handle assembly 68 or the foot switch 434 until thetissue impedance Z_(t) changes by a predetermined amount. A force orload is then applied to the clamp arm assembly 451 and the blade 79.During this period the ultrasonic transducer 50 mechanically activatesthe blade 79 at the first drive frequency f₁ and as a result, the tissue514 begins to desiccate from the ultrasonic action applied between theblade 79 and the one or more clamp pads 58 of the clamp arm assembly 451causing the tissue impedance Z_(t) to increase. Eventually, as thetissue is transected by the ultrasonic action and applied clamp force,the tissue impedance Z_(t) becomes very high or infinite as the tissuefully transects such that no conductive path exists between the blade 79and the conductive jacket 472. It will be appreciated by those skilledin the art that the drive current (I) output also may be stepped asdescribed with reference to FIGS. 6-8 based on the tissue impedanceZ_(t).

In one form, the tissue impedance Z_(t) may be monitored by theimpedance module 502 in accordance with the following process. Ameasurable RF current i1 is conveyed through the first energizingconductor 504 a to the blade 79, through the tissue 514, and back to theimpedance module 502 through the conductive jacket 472 and the secondconductor 504 b. As the tissue 514 is desiccated and cut by theultrasonic action of the blade 79 acting against the one or more clamppads 58, the impedance of the tissue 514 increases and thus the currenti1 in the return path, i.e., the second conductor 504 b, decreases. Theimpedance module 502 measures the tissue impedance Z_(t) and conveys arepresentative signal to the ADC 432 whose digital output 433 isprovided to the processor 400. The processor 400 calculates the tissueimpedance Z_(t) based on these measured values of v_(rf) and i_(rf). Theprocessor 400 steps the frequency by any suitable increment or decrementin response to changes in tissue impedance Z_(t). The processor 400controls the drive signals 416 and can make any necessary adjustments inamplitude and frequency in response to the tissue impedance Z_(t). Inone form, the processor 400 can cut off the drive signal 416 when thetissue impedance Z_(t) reaches a predetermined threshold value.

Accordingly, by way of example, and not limitation, in one form, theultrasonic surgical instrument 120 may be operated in accordance with aprogrammed stepped output algorithm to separate the inner muscle layerof a vessel from the adventitia layer prior to transecting and sealingthe vessel. As previously discussed, according to one step functionalgorithm, the processor 400 initially sets a first drive frequency f1that is significantly off resonance. The transducer 50 is activated toseparate the inner muscle layer of the vessel from the adventitia layerand the tissue impedance module 502 applies a subtherapeutic RF voltagev_(rf) signal to the blade 79. During this period T₁ of operation theprocessor 400 monitors the tissue impedance Z_(t) to determine when theinner muscle layer is transected or separated from the adventitia layer.The tissue impedance Z_(t) is correlated to the load applied to theblade 79, for example, when the tissue becomes desiccated or when thetissue is transected the tissue impedance Z_(t) becomes extremely highor infinite. The change in tissue impedance Z_(t) indicates that thevessel has been separated or transected from the inner muscle layer andthe generator 500 is deactivated for a second period of time T₂. Theprocessor 400 then sets the drive frequency to the resonant frequencyf_(o). The vessel is then grasped between the blade 79 and the clamp armassembly 451 and the transducer 50 is reactivated to transect and sealthe vessel. Continuous monitoring of the tissue impedance Z_(t) providesan indication of when the vessel is transected and sealed. Also, thetissue impedance Z_(t) may be monitored to provide an indication of thecompleteness of the tissue cutting and/or coagulating process or to stopthe activation of the ultrasonic generator 500 when the tissue impedanceZ_(t) reaches a predetermined threshold value. The threshold for thetissue impedance Z_(t) may be selected, for example, to indicate thatthe vessel has been transected. In one form, the tissue impedance Z_(t)may range between about 10 Ohms to about 1000 Ohms from an initial pointto a point just before the muscle layer is transected and sealed.

The applicants have discovered that experiments that run varying currentset points (both increasing and decreasing) and dwell times indicatethat the described forms can be used to separate the inner muscle layerfrom the outer adventitia layer prior to completing the transectionresulting in improved hemostasis and potentially lower total energy(heat) at the transection site. Furthermore, although the surgicalinstruments 100, 120 have been described in regards to thresholdimpedance detection schemes to determine when the muscle layer isseparated from the adventitia, other forms that do not employ anydetection scheme are within the scope of the present disclosure. Forexample, forms of the surgical instruments 100, 120 may be employed insimplified surgical systems wherein non-resonant power is applied toseparate the layers for a predetermined time of approximately 1 secondor less, prior to applying a resonant power to cut the tissue. The formsare not limited in this context.

Having described operational details of various forms of the surgicalsystems 19 (FIG. 1) and 190 (FIG. 10), operations for the above surgicalsystems 19, 190 may be further described generally in terms of a processfor cutting and coagulating tissue employing a surgical instrumentcomprising the input device 406 and the tissue impedance module 502.Although a particular process is described in connection with theoperational details, it can be appreciated that the process merelyprovides an example of how the general functionality described hereincan be implemented by the surgical systems 19, 190. Further, the givenprocess does not necessarily have to be executed in the order presentedherein unless otherwise indicated. As previously discussed, the inputdevice 406 may be employed to program the stepped output (e.g., current,frequency) to the ultrasonic transducer 50/blade 79 assembly.

FIG. 14 illustrates one form of a method 600 for driving an end effectorcoupled to an ultrasonic drive system of a surgical instrument. Themethod 600, and any of the other methods, algorithms, etc., describedherein, may be initiated in any suitable manner. For example, the method600 and any of the other methods, algorithms, etc. described herein maybe initiated in response to user input provided via any one orcombination of buttons, switches, and/or foot pedals including, forexample, those described herein. With reference to FIGS. 1-3, and 6-14,by way of example, and not limitation, the ultrasonic surgicalinstruments 100, 120 may be operated in accordance with the method 600to separate the inner muscle layer of a vessel from the adventitia layerprior to transecting and sealing the vessel. Accordingly, in variousforms, an end effector (e.g., end effector 81, 810) of a surgicalinstrument (e.g., surgical instrument 100, 120) may be driven inaccordance with the method 600. A generator (e.g., generator 30, 500) iscoupled to an ultrasonic drive system. The ultrasonic drive systemcomprises an ultrasonic transducer (e.g., ultrasonic transducer 50)coupled to a waveguide (e.g., waveguide 80). The end effector 81 iscoupled to the waveguide 80. The ultrasonic drive system and endeffector 81 are configured to resonate at a resonant frequency (e.g.,55.5 kHz). In one form, at 602, the generator 30 generates a firstultrasonic drive signal. At 604, the ultrasonic transducer 50 isactuated with the first ultrasonic drive signal for a first period inresponse to activating a switch (e.g., switch 34) on a handle assembly(e.g., handle assembly 68) or a foot switch (e.g., foot switch 434)connected to the generator 30. After the first period, at 606, thegenerator 30 generates a second ultrasonic drive signal. At 608, theultrasonic transducer 50 is actuated with the second ultrasonic drivesignal for a second period in response to activating the switch 34 onthe handle assembly 68 or the foot switch 434 connected to the generator30. The first drive signal is different from the second drive signalover the respective first and second periods. The first and second drivesignals define a step function waveform over the first and secondperiods.

In one form, the generator 30 generates a third ultrasonic drive signal.The ultrasonic transducer 50 is actuated with the third ultrasonic drivesignal for a third period. The third drive signal is different from thefirst second drive signals over the first, second, and third periods.The first, second, and third drive signals define a step functionwaveform over the first, second, and third periods. In one form,generating the first, second, and third ultrasonic drive signalscomprises generating a corresponding first, second, and third drivecurrent and actuating the ultrasonic transducer 50 with the first drivecurrent for the first period, actuating the ultrasonic transducer 50with the second drive current for the second period, and actuating theultrasonic transducer 50 with the third drive current for the thirdperiod.

In certain forms, the first, second and third drive currents mayincrease, decrease or stay the same relative to one another. Forexample, in certain forms, some or all of the first, second and thirddrive currents are equal. Also, in certain forms, the first, second andthird periods may take any suitable value including, for example,fractions of a second, minutes, hours, etc. In one example form, some orall of the first, second and third periods may be 55 seconds.

In one form, the generator 30 generates the first ultrasonic drivesignal at a first frequency, which is different from the resonantfrequency. The ultrasonic transducer 50 is then actuated with the firstultrasonic drive signal at the first frequency for the first period.Actuation at the first frequency provides a first level of mechanicalvibration to the end effector 81 suitable for separating a first tissuefrom a second tissue, for example, to separate the inner muscle layer ofa vessel from the adventitia layer. The generator 30 generates thesecond ultrasonic drive signal at the resonant frequency, e.g., 55.5kHz, and the actuates the ultrasonic transducer 50 with the secondultrasonic drive signal at the resonant frequency for the second periodsubsequent to the first period. Actuation at the second, resonantfrequency, provides a second level of mechanical vibration to the endeffector 81 suitable for transecting and sealing the first tissue, suchas the vessel, once it separated from the inner muscle layer. In oneform, the second ultrasonic drive signal at the resonant frequency isgenerated automatically by the generator 30 after the first period. Inone form, the first frequency is substantially different from theresonant frequency and the first period is less than about one second.For example, in one form, the first frequency is defined by thefollowing equation: f₁=2*f_(o), wherein f₁ is the first frequency andf_(o) is the resonant frequency. In another form, the first frequency isdefined by the following equation: f₁=f_(o)/2, wherein f₁ is the firstfrequency and f_(o) is the resonant frequency. The first, second, andthird ultrasonic drive signals are also envisioned to excite bevibratory modes of the ultrasonic transducer 50 in longitudinal,flexural, and torsional modes and harmonics thereof.

In one form, the generator 30 monitors a measurable characteristic ofthe ultrasonic drive system and generates any one of the first andsecond drive signals based on the measured characteristic. For example,the generator 30 monitors the impedance Z of the ultrasonic transducer50. The generator 30 comprises electronic circuitry suitable formeasuring the impedance of the transducer 50. For example, a currentsense circuit (e.g., current sense circuit 426) senses the currentflowing through the transducer 50 and a voltage sense circuit (e.g.,voltage sense circuit 428) senses the output voltage applied to thetransducer 50. A multiplexer (e.g., multiplexer 430) routes theappropriate analog signal to an analog-to-digital converter (e.g., ADC432), whose digital output is provided to a processor (e.g., processor400). The processor 400 calculates the transducer impedance Z based onthe measured values of current and voltage.

In one form, the generator 500 comprises an impedance module (e.g.,tissue impedance module 502) to measure the impedance of a tissueportion contacting an end effector (e.g., end effector 810). Theimpedance module 502 includes an RF oscillator (e.g., RF oscillator 506)to generate a subtherapeutic RF signal. The subtherapeutic RF signal isapplied to a blade (e.g., blade 79) portion of the end effector 810,which forms an energizing electrode. The tissue portion is graspedbetween the end effector 810 and a return electrode of a clamp armassembly (e.g., clamp arm assembly 451) and the impedance of the tissue(e.g., tissue 514). The tissue impedance is then measured by a voltagesense circuit (e.g., voltage sense circuit 508) and current sensecircuit (e.g., current sense circuit 510) and of the impedance module502. These signals are applied to the ADC 432 via the multiplexer 430.The digital output of the ADC 432 is provided to the processor 400,which calculates the tissue impedance Z_(t) based on the measured valuesof current through the tissue and the voltage applied to the blade 79portion of the end effector 810.

FIGS. 15A-C illustrate various forms of logic flow diagrams of 700, 800,900 of operations for determining a change of state of tissue beingmanipulated by an ultrasonic surgical instrument and providing feedbackto the user to indicate that the tissue has undergone such change ofstate or that there is a high likelihood that the tissue has undergonesuch change of state. The operations 700, 800, 900, and variouspermutations thereof, may be utilized in any implementation where thestate of tissue is monitored. For example, one or more of the operations700, 800, 900, etc. may be executed automatically when the surgicalsystem is in use. Also, operations 700, 800, 900, etc. may be triggeredbased on clinician input, for example, via one or more buttons, switchesand pedals, etc. (e.g., the buttons, switches and pedals, etc. describedherein). As used herein, the tissue may undergo a change of state whenthe tissue is separated from other layers of tissue or bone, when thetissue is cut or transected, when the tissue is coagulated, and so forthwhile being manipulated with an end effector of an ultrasonic surgicalinstrument, such as, for example, the end effector 81, 810 of theultrasonic surgical instrument 100, 120 shown in FIGS. 1 and 10. Achange in tissue state may be determined based on the likelihood of anoccurrence of a tissue separation event.

In various forms, the feedback is provided by the output indicator 412shown in FIGS. 9 and 11. The output indicator 412 is particularly usefulin applications where the tissue being manipulated by the end effector81, 810 is out of the user's field of view and the user cannot see whena change of state occurs in the tissue. The output indicator 412communicates to the user that a change in tissue state has occurred asdetermined in accordance with the operations described with respect tothe logic flow diagrams 700, 800, 900. As previously discussed, theoutput indicator 412 may be configured to provide various types offeedback to the user including, without limitation, visual, audible,and/or tactile feedback to indicate to the user (e.g., surgeon,clinician) that the tissue has undergone a change of state or conditionof the tissue. By way of example, and not limitation, as previouslydiscussed, visual feedback comprises any type of visual indicationdevice including incandescent lamps or LEDs, graphical user interface,display, analog indicator, digital indicator, bar graph display, digitalalphanumeric display. By way of example, and not limitation, audiblefeedback comprises any type of buzzer, computer generated tone,computerized speech, VUI to interact with computers through avoice/speech platform. By way of example, and not limitation, tactilefeedback comprises any type of vibratory feedback provided through theinstrument housing handle assembly 68. The change of state of the tissuemay be determined based on transducer and tissue impedance measurementsas previously described, or based on voltage, current, and frequencymeasurements in accordance with the operations described with respect tothe logic flow diagrams 700, 800, 900 described below with respect toFIGS. 15A-C.

In one form, the logic flow diagrams 700, 800, 900 may be implemented asexecutable modules (e.g., algorithms) comprising computer readableinstructions to be executed by the processor 400 (FIGS. 9, 11, 14)portion of the generator 30, 500. In various forms, the operationsdescribed with respect to the logic flow diagrams 700, 800, 900 may beimplemented as one or more software components, e.g., programs,subroutines, logic; one or more hardware components, e.g., processors,DSPs, PLDs, ASICs, circuits, registers; and/or combinations of softwareand hardware. In one form, the executable instructions to perform theoperations described by the logic flow diagrams 700, 800, 900 may bestored in memory. When executed, the instructions cause the processor400 to determine a change in tissue state in accordance with theoperations described in the logic flow diagrams 800 and 900 and providefeedback to the user by way of the output indicator 412. In accordancewith such executable instructions, the processor 400 monitors andevaluates the voltage, current, and/or frequency signal samplesavailable from the generator 30, 500 and according to the evaluation ofsuch signal samples determines whether a change in tissue state hasoccurred. As further described below, a change in tissue state may bedetermined based on the type of ultrasonic instrument and the powerlevel that the instrument is energized at. In response to the feedback,the operational mode of the ultrasonic surgical instrument 100, 120 maybe controlled by the user or may be automatically or semi-automaticallycontrolled.

FIG. 15A illustrates a logic flow diagram 700 of one form of determininga change in tissue state and activating the output indicator 412accordingly. With reference now to the logic flow diagram 700 shown inFIG. 15A and the drive system 32 of the generator 30 shown in FIG. 9, at702, the processor 400 portion of the drive system 32 samples thevoltage (v), current (i), and frequency (f) signals of the generator 30.In the illustrated form, at 704, the frequency and voltage signalsamples are analyzed separately to determine the corresponding frequencyinflection and/or voltage drop points. In other forms, the currentsignal samples may be separately analyzed in addition to the voltage andfrequency signal samples or in place of the voltage signal samples. At706, the present frequency signal sample is provided to a frequencyinflection point analysis module for determining a change in tissuestate as illustrated in the logic flow diagram 800 in FIG. 15B. At 708,the present voltage signal sample is provided to a voltage drop pointanalysis module for determining a change in tissue state as illustratedin the logic flow diagram 900 in FIG. 15C.

The frequency inflection point analysis module and the voltage droppoint analysis module determine when a change in tissue state hasoccurred based on correlated empirical data associated with a particularultrasonic instrument type and the energy level at which the instrumentis driven. At 714, the results 710 from the frequency inflection pointanalysis module and/or the results 712 from the voltage drop pointanalysis module are read by the processor 400. The processor 400determines 716 whether the frequency inflection point result 710 and/orthe voltage drop point result 712 indicates a change in tissue state. Ifthe results 710, 714 do not indicate a change in tissue state, theprocessor 400 continues along the “No” branch to 702 and reads anadditional voltage and frequency signal sample from the generator 30. Informs that utilize the generator current in the analysis, the processor400 would now also read an additional current signal sample from thegenerator 30. If the results 710, 714 indicate a sufficient change intissue state, the processor 400 continues along the “Yes” branch to 718and activates the output indicator 412.

As previously discussed, the output indicator 412 may provide visual,audible, and/or tactile feedback to alert the user of the ultrasonicsurgical instrument 100, 120 that a change in tissue state has occurred.In various forms, in response to the feedback from the output indicator412, the operational mode of the generator 30, 500 and/or the ultrasonicinstrument 100, 120 may be controlled manually, automatically, orsemi-automatically. The operational modes include, without limitation,disconnecting or shutting down the output power of the generator 30,500, reducing the output power of the generator 30, 500, cycling theoutput power of the generator 30, 500, pulsing the output power of thegenerator 30, 500, and/or outputting a high-power momentary surge fromthe generator 30, 500. The operational modes of the ultrasonicinstrument in response to the change in tissue state can be selected,for example, to minimize heating effects of the end effector 81, 810,e.g., of the clamp pad 58 (FIGS. 1-3), to prevent or minimize possibledamage to the surgical instrument 100, 120 and/or surrounding tissue.This is advantageous because heat is generated rapidly when thetransducer 50 is activated with nothing between the jaws of the endeffector 81, 810 as is the case when a change in tissue state occurssuch as when tissue has substantially separated from the end effector.

FIG. 15B is a logic flow diagram 800 illustrating one form of theoperation of the frequency inflection point analysis module. At 802, afrequency sample is received by the processor 400 from 706 of the logicflow diagram 700. At 804, the processor 400 calculates an exponentiallyweighted moving average (EWMA) for the frequency inflection analysis.The EWMA is calculated to filter out noise from the generator from thefrequency samples. The EWMA is calculated in accordance with a frequencymoving average equation 806 and an alpha value (α) 808:S _(tf) =αY _(tf)+(1−α)S _(tf)−1  (2)

Where:

S_(tf)=the current moving average of the sampled frequency signal;

S_(tf-1)=the previous moving average of the sampled frequency signal;

α=the smoothing factor; and

Y_(tf)=current data point of the sampled frequency signal.

The α value 808 may vary from about 0 to about 1 in accordance with adesired filtering or smoothing factor, wherein small α values 808approaching about 0 provide a large amount of filtering or smoothing andlarge α values 808 approaching about 1 provide a small amount offiltering or smoothing. The α value 808 may be selected based on theultrasonic instrument type and power level. In one form, blocks 804,806, and 808 may be implemented as a variable digital low pass filter810 with the α value 808 determining the cutoff point of the filter 810.Once the frequency samples are filtered, the slope of the frequencysamples is calculated at 812 as:Frequency Slope=deltaf/deltat  (3)

The calculated Frequency Slope data points are provided to a “slowresponse” moving average filter 814 to calculate the EWMA moving averagefor the Frequency Slope to further reduce system noise. In one form, the“slow response” moving average filter 814 may be implemented bycalculating the EWMA for the Frequency Slope at 818 in accordance withthe frequency slope moving average equation 820 and alpha value (α′)822:S′ _(tf) =α′Y′ _(tf)+(1−α′)S′ _(tf-1)  (4)

Where:

S′_(tf)=the current moving average of the frequency slope of the sampledfrequency signal;

S′_(tf-1)=the previous moving average of the frequency slope of thesampled frequency signal;

α′=the smoothing factor; and

Y′_(tf)=current slope data point of the sampled frequency signal.

The α″ value 822 varies from about 0 to about 1, as previously discussedwith respect to digital filter block 810 in accordance with a desiredfiltering or smoothing factor, wherein small α″ value 822 approaching 0provide a large amount of filtering or smoothing and large α″ value 822approaching 1 provide a small amount of filtering or smoothing. The α″value 822 may be selected based on the ultrasonic instrument type andpower level.

The calculated Frequency Slope data points are provided to a “fastresponse” filter 816 to calculate the moving average for the FrequencySlope. At 824, the “fast response” filter 816 calculates the movingaverage for the Frequency Slope based on a number of data points 826.

In the illustrated form, the output of the “slow response” movingaverage filter 814 “Slope EWMA” is applied to a (+) input of an adder828 and the output of the “fast response” filter 816 “Slope Avg” isapplied to (−) input of the adder 828. The adder 828 computes thedifference between the outputs of the “slow response” moving averagefilter 814 and the “fast response” filter 816. The difference betweenthese outputs is compared at 830 to a predetermined limit 832. The limit832 is determined based on the type of ultrasonic instrument and thepower level at which the particular type of ultrasonic instrument isenergized at. The limit 832 value may be predetermined and stored inmemory in the form of a look-up table or the like. If the differencebetween the “Slope EWMA” and the “Slope Avg” is not greater than thelimit 832, the processor 400 continues along the “No” branch and returnsa value 834 to the results 710 block that indicates that no inflectionpoint was found in the sampled frequency signal and, therefore, nochange in tissue state was detected. However, if the difference betweenthe “Slope EWMA” and the “Slope Avg” is greater than the limit 832, theprocessor 400 continues along the “Yes” branch and determines that afrequency inflection point 836 was found and returns point index 838 tothe results 710 block indicating that an inflection point was found inthe sampled frequency data and, therefore, a change in tissue state wasdetected. As previously discussed with reference to FIG. 15A, if afrequency inflection point 836 is found, then, at 718 (FIG. 15A) theprocessor 400 activates the change in tissue state indicator 718.

FIG. 15C is a logic flow diagram 900 illustrating one form of theoperation of the voltage drop analysis module. At 902, a voltage sampleis received by the processor 400 from 708 of the logic flow diagram 700.At 904, the processor 400 calculates an exponentially weighted movingaverage (EWMA) for the voltage drop point analysis. The EWMA iscalculated to filter out noise from the generator from the voltagesamples. The EWMA is calculated in accordance with a voltage movingaverage equation 906 and an alpha value (α) 908:S _(tv) =αY _(tv)+(1−α)S _(tv-1)  (5)

Where:

S_(tv)=the current moving average of the sampled voltage signal;

S_(tv-1)=the previous moving average of the sampled voltage signal;

α=the smoothing factor; and

Y_(tf)=current data point of the sampled voltage signal.

As previously discussed, the α value 908 may vary from 0 to 1 inaccordance with a desired filtering or smoothing factor and may beselected based on the ultrasonic instrument type and power level. In oneform, blocks 904, 906, and 908 may be implemented as a variable digitallow pass filter 910 with the α value 908 determining the cutoff point ofthe filter 910. Once the voltage samples are filtered, the slope of thevoltage samples is calculated at 912 as:Voltage Slope=deltav/deltat  (6)

The calculated Voltage Slope data points are provided to a “slowresponse” moving average filter 914 to calculate the EWMA moving averagefor the Voltage Slope to further reduce system noise. In one form, the“slow response” moving average filter 914 may be implemented bycalculating the EWMA for the Voltage Slope at 918 in accordance with thevoltage slope moving average equation 920 and alpha value (α′) 822:S′ _(tv) =α′Y′ _(tv)+(1−α′)S′ _(tv-1)  (7)

Where:

S′_(tv)=the current moving average of the voltage slope of the sampledvoltage signal;

S′_(tv-1)=the previous moving average of the voltage slope of thesampled voltage signal;

α″=the smoothing factor; and

Y′_(tv)=current slope data point of the sampled voltage signal.

The α″ value 922 varies from about 0 to about 1, as previously discussedwith respect to digital filter block 910 in accordance with a desiredfiltering or smoothing factor, wherein small α″ value 922 approachingabout 0 provide a large amount of filtering or smoothing and large α′value 922 approaching about 1 provide a small amount of filtering orsmoothing. The α″ value 922 may be selected based on the ultrasonicinstrument type and power level.

The calculated Voltage Slope data points are provided to a “fastresponse” filter 916 to calculate the moving average for the VoltageSlope. At 924, the “fast response” filter 916 calculates the movingaverage for the Voltage Slope based on a number of data points 926.

In the illustrated form, the output of the “slow response” movingaverage filter 914 “Slope EWMA” is applied to a (+) input of an adder928 and the output of the “fast response” filter 916 “Slope Avg” isapplied to (−) input of the adder 928. The adder 928 computes thedifference between the outputs of the “slow response” moving averagefilter 914 and the “fast response” filter 916. The difference betweenthese outputs is compared at 930 to a predetermined limit 932. The limit932 is determined based on the type of ultrasonic instrument and thepower level at which the particular type of ultrasonic instrument isenergized at. The limit 932 value may be predetermined and stored inmemory in the form of a look-up table or the like. If the differencebetween the “Slope EWMA” and the “Slope Avg” is not greater than thelimit 932, the processor 400 continues along the “No” branch and resetsa counter to zero at 940, then returns a value 934 to the results 710block that indicates that no voltage drop point was found in the sampledvoltage signals and, therefore, no change in tissue state was detected.However, if the difference between the “Slope EWMA” and the “Slope Avg”is greater than the limit 932, the processor 400 continues along the“Yes” branch and increments a counter at 942. At 944, the processor 400decides whether the counter is greater than 1, or some otherpredetermined threshold value for example. In other words, the processor400 takes at least two data points in regards to the voltage drop point.If the counter is not greater than the threshold (e.g., 1 in theillustrated form) the processor 400 continues along the “No” branch andreturns a value 934 to the results 710 block that indicates that novoltage drop point was found in the sampled voltage signals and,therefore, no change in tissue state was detected. If the counter isgreater than the threshold (e.g., 1 in the illustrated form) theprocessor 400 continues along the “Yes” branch and determines that avoltage drop point 936 was found and returns a point index 938 to theresults 712 block indicating that a voltage drop point was found in thesampled voltage signals and, therefore, a change in tissue state wasdetected. As previously discussed with reference to FIG. 15A, if avoltage point 836 is found, then, at 718 (FIG. 15A) the processor 400activates the change in tissue state indicator 718.

FIG. 16 illustrates one form of a surgical system 1000 comprising agenerator 1002 and various surgical instruments 1004, 1006 usabletherewith. FIG. 16A is a diagram of the ultrasonic surgical instrument1004 of FIG. 16. The generator 1002 is configurable for use withsurgical devices. According to various forms, the generator 1002 may beconfigurable for use with different surgical devices of different typesincluding, for example, the ultrasonic device 1004 and electrosurgicalor RF surgical devices, such as, the RF device 1006. Although in theform of FIG. 16, the generator 1002 is shown separate from the surgicaldevices 1004, 1006, in one form, the generator 1002 may be formedintegrally with either of the surgical devices 1004, 1006 to form aunitary surgical system. The generator 1002 comprises an input device1045 located on a front panel of the generator 1002 console. The inputdevice 1045 may comprise any suitable device that generates signalssuitable for programming the operation of the generator 1002.

FIG. 17 is a diagram of the surgical system 1000 of FIG. 16. In variousforms, the generator 1002 may comprise several separate functionalelements, such as modules and/or blocks. Different functional elementsor modules may be configured for driving the different kinds of surgicaldevices 1004, 1006. For example, an ultrasonic generator module 1008 maydrive ultrasonic devices such as the ultrasonic device 1004. Anelectrosurgery/RF generator module 1010 may drive the electrosurgicaldevice 1006. For example, the respective modules 1008, 1010 may generaterespective drive signals for driving the surgical devices 1004, 1006. Invarious forms, the ultrasonic generator module 1008 and/or theelectrosurgery/RF generator module 1010 each may be formed integrallywith the generator 1002. Alternatively, one or more of the modules 1008,1010 may be provided as a separate circuit module electrically coupledto the generator 1002. (The modules 1008 and 1010 are shown in phantomto illustrate this option.) Also, in some forms, the electrosurgery/RFgenerator module 1010 may be formed integrally with the ultrasonicgenerator module 1008, or vice versa. Also, in some forms, the generator1002 may be omitted entirely and the modules 1008, 1010 may be executedby processors or other hardware within the respective instruments 1004,1006.

In accordance with the described forms, the ultrasonic generator module1008 may produce a drive signal or signals of particular voltages,currents, and frequencies, e.g., 55,500 cycles per second (Hz). Thedrive signal or signals may be provided to the ultrasonic device 1004,and specifically to the transducer 1014, which may operate, for example,as described above. The transducer 1014 and a waveguide extendingthrough the shaft 1015 (waveguide not shown in FIG. 16A) maycollectively form an ultrasonic drive system driving an ultrasonic blade1017 of an end effector 1026. In one form, the generator 1002 may beconfigured to produce a drive signal of a particular voltage, current,and/or frequency output signal that can be stepped or otherwise modifiedwith high resolution, accuracy, and repeatability.

The generator 1002 may be activated to provide the drive signal to thetransducer 1014 in any suitable manner. For example, the generator 1002may comprise a foot switch 1020 coupled to the generator 1002 via afootswitch cable 1022. A clinician may activate the transducer 1014 bydepressing the foot switch 1020. In addition, or instead of the footswitch 1020 some forms of the ultrasonic device 1004 may utilize one ormore switches positioned on the hand piece that, when activated, maycause the generator 1002 to activate the transducer 1014. In one form,for example, the one or more switches may comprise a pair of togglebuttons 1036 a, 1036 b (FIG. 16A), for example, to determine anoperating mode of the device 1004. When the toggle button 1036 a isdepressed, for example, the ultrasonic generator 1002 may provide amaximum drive signal to the transducer 1014, causing it to producemaximum ultrasonic energy output. Depressing toggle button 1036 b maycause the ultrasonic generator 1002 to provide a user-selectable drivesignal to the transducer 1014, causing it to produce less than themaximum ultrasonic energy output. The device 1004 additionally oralternatively may comprise a second switch (not shown) to, for example,indicate a position of a jaw closure trigger for operating jaws of theend effector 1026. Also, in some forms, the ultrasonic generator 1002may be activated based on the position of the jaw closure trigger,(e.g., as the clinician depresses the jaw closure trigger to close thejaws, ultrasonic energy may be applied).

Additionally or alternatively, the one or more switches may comprises atoggle button 1036 c that, when depressed, causes the generator 1002 toprovide a pulsed output. The pulses may be provided at any suitablefrequency and grouping, for example. In certain forms, the power levelof the pulses may be the power levels associated with toggle buttons1036 a, 1036 b (maximum, less than maximum), for example.

It will be appreciated that a device 1004 may comprise any combinationof the toggle buttons 1036 a, 1036 b, 1036 c. For example, the device1004 could be configured to have only two toggle buttons: a togglebutton 1036 a for producing maximum ultrasonic energy output and atoggle button 1036 c for producing a pulsed output at either the maximumor less than maximum power level. In this way, the drive signal outputconfiguration of the generator 1002 could be 5 continuous signals and 5or 4 or 3 or 2 or 1 pulsed signals. In certain forms, the specific drivesignal configuration may be controlled based upon, for example, EEPROMsettings in the generator 1002 and/or user power level selection(s).

In certain forms, a two-position switch may be provided as analternative to a toggle button 1036 c. For example, a device 1004 mayinclude a toggle button 1036 a for producing a continuous output at amaximum power level and a two-position toggle button 1036 b. In a firstdetented position, toggle button 1036 b may produce a continuous outputat a less than maximum power level, and in a second detented positionthe toggle button 1036 b may produce a pulsed output (e.g., at either amaximum or less than maximum power level, depending upon the EEPROMsettings).

In accordance with the described forms, the electrosurgery/RF generatormodule 1010 may generate a drive signal or signals with output powersufficient to perform bipolar electrosurgery using radio frequency (RF)energy. In bipolar electrosurgery applications, the drive signal may beprovided, for example, to electrodes of the electrosurgical device 1006,for example. Accordingly, the generator 1002 may be configured fortherapeutic purposes by applying electrical energy to the tissuesufficient for treating the tissue (e.g., coagulation, cauterization,tissue welding).

The generator 1002 may comprise an input device 1045 (FIG. 16) located,for example, on a front panel of the generator 1002 console. The inputdevice 1045 may comprise any suitable device that generates signalssuitable for programming the operation of the generator 1002. Inoperation, the user can program or otherwise control operation of thegenerator 1002 using the input device 1045. The input device 1045 maycomprise any suitable device that generates signals that can be used bythe generator (e.g., by one or more processors contained in thegenerator) to control the operation of the generator 1002 (e.g.,operation of the ultrasonic generator module 1008 and/orelectrosurgery/RF generator module 1010). In various forms, the inputdevice 1045 includes one or more of buttons, switches, thumbwheels,keyboard, keypad, touch screen monitor, pointing device, remoteconnection to a general purpose or dedicated computer. In other forms,the input device 1045 may comprise a suitable user interface, such asone or more user interface screens displayed on a touch screen monitor,for example. Accordingly, by way of the input device 1045, the user canset or program various operating parameters of the generator, such as,for example, current (I), voltage (V), frequency (f), and/or period (T)of a drive signal or signals generated by the ultrasonic generatormodule 1008 and/or electrosurgery/RF generator module 1010.

The generator 1002 may also comprise an output device 1047 (FIG. 16),such as an output indicator, located, for example, on a front panel ofthe generator 1002 console. The output device 1047 includes one or moredevices for providing a sensory feedback to a user. Such devices maycomprise, for example, visual feedback devices (e.g., a visual feedbackdevice may comprise incandescent lamps, light emitting diodes (LEDs),graphical user interface, display, analog indicator, digital indicator,bar graph display, digital alphanumeric display, LCD display screen, LEDindicators), audio feedback devices (e.g., an audio feedback device maycomprise speaker, buzzer, audible, computer generated tone, computerizedspeech, voice user interface (VUI) to interact with computers through avoice/speech platform), or tactile feedback devices (e.g., a tactilefeedback device comprises any type of vibratory feedback, hapticactuator).

Although certain modules and/or blocks of the generator 1002 may bedescribed by way of example, it can be appreciated that a greater orlesser number of modules and/or blocks may be used and still fall withinthe scope of the forms. Further, although various forms may be describedin terms of modules and/or blocks to facilitate description, suchmodules and/or blocks may be implemented by one or more hardwarecomponents, e.g., processors, Digital Signal Processors (DSPs),Programmable Logic Devices (PLDs), Application Specific IntegratedCircuits (ASICs), circuits, registers and/or software components, e.g.,programs, subroutines, logic and/or combinations of hardware andsoftware components. Also, in some forms, the various modules describedherein may be implemented utilizing similar hardware positioned withinthe instruments 100, 120, 1004, 1006 (i.e., the generator 30, 50, 1002may be omitted).

In one form, the ultrasonic generator drive module 1008 andelectrosurgery/RF drive module 1010 may comprise one or more embeddedapplications implemented as firmware, software, hardware, or anycombination thereof. The modules 1008, 1010 may comprise variousexecutable modules such as software, programs, data, drivers,application program interfaces (APIs), and so forth. The firmware may bestored in nonvolatile memory (NVM), such as in bit-masked read-onlymemory (ROM) or flash memory. In various implementations, storing thefirmware in ROM may preserve flash memory. The NVM may comprise othertypes of memory including, for example, programmable ROM (PROM),erasable programmable ROM (EPROM), electrically erasable programmableROM (EEPROM), or battery backed random-access memory (RAM) such asdynamic RAM (DRAM), Double-Data-Rate DRAM (DDRAM), and/or synchronousDRAM (SDRAM).

In one form, the modules 1008, 1010 comprise a hardware componentimplemented as a processor for executing program instructions formonitoring various measurable characteristics of the devices 1004, 1006and generating a corresponding output control signals for operating thedevices 1004, 1006. In forms in which the generator 1002 is used inconjunction with the device 1004, the output control signal may drivethe ultrasonic transducer 1014 in cutting and/or coagulation operatingmodes. Electrical characteristics of the device 1004 and/or tissue maybe measured and used to control operational aspects of the generator1002 and/or provided as feedback to the user. In forms in which thegenerator 1002 is used in conjunction with the device 1006, the outputcontrol signal may supply electrical energy (e.g., RF energy) to the endeffector 1032 in cutting, coagulation and/or desiccation modes.Electrical characteristics of the device 1006 and/or tissue may bemeasured and used to control operational aspects of the generator 1002and/or provide feedback to the user. In various forms, as previouslydiscussed, the hardware component may be implemented as a DSP, PLD,ASIC, circuits, and/or registers. In one form, the processor may beconfigured to store and execute computer software program instructionsto generate the step function output signals for driving variouscomponents of the devices 1004, 1006, such as the ultrasonic transducer1014 and the end effectors 1026, 1032.

FIG. 18 illustrates an equivalent circuit 1050 of an ultrasonictransducer, such as the ultrasonic transducer 1014, according to oneform. The circuit 1050 comprises a first “motional” branch having aserially connected inductance L_(s), resistance R_(s) and capacitanceC_(s) that define the electromechanical properties of the resonator, anda second capacitive branch having a static capacitance C_(o). Drivecurrent I_(g) may be received from a generator at a drive voltage V_(g),with motional current I_(m) flowing through the first branch and currentI_(g)-I_(m) flowing through the capacitive branch. Control of theelectromechanical properties of the ultrasonic transducer may beachieved by suitably controlling I_(g) and V_(g). As explained above,conventional generator architectures may include a tuning inductor L_(t)(shown in phantom in FIG. 18) for tuning out in a parallel resonancecircuit the static capacitance Co at a resonant frequency so thatsubstantially all of generator's current output I_(g) flows through themotional branch. In this way, control of the motional branch currentI_(m) is achieved by controlling the generator current output I_(g). Thetuning inductor L_(t) is specific to the static capacitance C_(o) of anultrasonic transducer, however, and a different ultrasonic transducerhaving a different static capacitance requires a different tuninginductor L_(t). Moreover, because the tuning inductor L_(t) is matchedto the nominal value of the static capacitance Co at a single resonantfrequency, accurate control of the motional branch current I_(m) isassured only at that frequency, and as frequency shifts down withtransducer temperature, accurate control of the motional branch currentis compromised.

Forms of the generator 1002 do not rely on a tuning inductor L_(t) tomonitor the motional branch current I_(m). Instead, the generator 1002may use the measured value of the static capacitance C_(o) in betweenapplications of power for a specific ultrasonic surgical device 1004(along with drive signal voltage and current feedback data) to determinevalues of the motional branch current I_(m) on a dynamic and ongoingbasis (e.g., in real-time). Such forms of the generator 1002 aretherefore able to provide virtual tuning to simulate a system that istuned or resonant with any value of static capacitance C_(o) at anyfrequency, and not just at single resonant frequency dictated by anominal value of the static capacitance C_(o).

FIG. 19 is a simplified block diagram of one form of the generator 1002for proving inductorless tuning as described above, among otherbenefits. Additional details of the generator 1002 are described incommonly assigned and contemporaneously filed U.S. patent applicationSer. No. 12/896,360, titled “Surgical Generator For Ultrasonic AndElectrosurgical Devices”, the disclosure of which is incorporated hereinby reference in its entirety. With reference to FIG. 19, the generator1002 may comprise a patient isolated stage 1052 in communication with anon-isolated stage 1054 via a power transformer 1056. A secondarywinding 1058 of the power transformer 1056 is contained in the isolatedstage 1052 and may comprise a tapped configuration (e.g., acenter-tapped or a non-center-tapped configuration) to define drivesignal outputs 1060 a, 1060 b, 1060 c for outputting drive signals todifferent surgical devices, such as, for example, an ultrasonic surgicaldevice 1004 and an electrosurgical device 1006. In particular, drivesignal outputs 1060 a, 1060 c may output an ultrasonic drive signal(e.g., a 420V RMS drive signal) to an ultrasonic surgical device 1004,and drive signal outputs 1060 b, 1060 c may output an electrosurgicaldrive signal (e.g., a 100V RMS drive signal) to an electrosurgicaldevice 1006, with output 1060 b corresponding to the center tap of thepower transformer 1056.

In certain forms, the ultrasonic and electrosurgical drive signals maybe provided simultaneously to distinct surgical instruments and/or to asingle surgical instrument having the capability to deliver bothultrasonic and electrosurgical energy to tissue. An example of a blade79 and clamp arm assembly 415 of one example form of such a surgicalinstrument is provided above in conjunction with FIG. 13. It will beappreciated that the electrosurgical signal, provided either to adedicated electrosurgical instrument and/or to a combinedultrasonic/electrosurgical instrument may be either a therapeutic orsub-therapeutic level signal.

The non-isolated stage 1054 may comprise a power amplifier 1062 havingan output connected to a primary winding 1064 of the power transformer1056. In certain forms the power amplifier 1062 may be comprise apush-pull amplifier. For example, the non-isolated stage 1054 mayfurther comprise a logic device 1066 for supplying a digital output to adigital-to-analog converter (DAC) 1068, which in turn supplies acorresponding analog signal to an input of the power amplifier 1062. Incertain forms the logic device 1066 may comprise a programmable gatearray (PGA), a field-programmable gate array (FPGA), programmable logicdevice (PLD), among other logic circuits, for example. The logic device1066, by virtue of controlling the input of the power amplifier 1062 viathe DAC 1068, may therefore control any of a number of parameters (e.g.,frequency, waveform shape, waveform amplitude) of drive signalsappearing at the drive signal outputs 1060 a, 1060 b, 1060 c. In certainforms and as discussed below, the logic device 1066, in conjunction witha processor (e.g., a digital signal processor discussed below), mayimplement a number of digital signal processing (DSP)-based and/or othercontrol algorithms to control parameters of the drive signals output bythe generator 1002.

Power may be supplied to a power rail of the power amplifier 1062 by aswitch-mode regulator 1070. In certain forms the switch-mode regulator1070 may comprise an adjustable buck regulator, for example. Thenon-isolated stage 1054 may further comprise a first processor 1074,which in one form may comprise a DSP processor such as an Analog DevicesADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass., forexample, although in various forms any suitable processor may beemployed. In certain forms the processor 1074 may control operation ofthe switch-mode power converter 1070 responsive to voltage feedback datareceived from the power amplifier 1062 by the DSP processor 1074 via ananalog-to-digital converter (ADC) 1076. In one form, for example, theDSP processor 1074 may receive as input, via the ADC 1076, the waveformenvelope of a signal (e.g., an RF signal) being amplified by the poweramplifier 1062. The DSP processor 1074 may then control the switch-moderegulator 1070 (e.g., via a pulse-width modulated (PWM) output) suchthat the rail voltage supplied to the power amplifier 1062 tracks thewaveform envelope of the amplified signal. By dynamically modulating therail voltage of the power amplifier 1062 based on the waveform envelope,the efficiency of the power amplifier 1062 may be significantly improvedrelative to a fixed rail voltage amplifier schemes.

In certain forms, the logic device 1066, in conjunction with the DSPprocessor 1074, may implement a direct digital synthesizer (DDS) controlscheme to control the waveform shape, frequency and/or amplitude ofdrive signals output by the generator 1002. In one form, for example,the logic device 1066 may implement a DDS control algorithm by recallingwaveform samples stored in a dynamically-updated look-up table (LUT),such as a RAM LUT, which may be embedded in an FPGA. This controlalgorithm is particularly useful for ultrasonic applications in which anultrasonic transducer, such as the ultrasonic transducer 1014, may bedriven by a clean sinusoidal current at its resonant frequency. Becauseother frequencies may excite parasitic resonances, minimizing orreducing the total distortion of the motional branch current maycorrespondingly minimize or reduce undesirable resonance effects.Because the waveform shape of a drive signal output by the generator1002 is impacted by various sources of distortion present in the outputdrive circuit (e.g., the power transformer 1056, the power amplifier1062), voltage and current feedback data based on the drive signal maybe input into an algorithm, such as an error control algorithmimplemented by the DSP processor 1074, which compensates for distortionby suitably pre-distorting or modifying the waveform samples stored inthe LUT on a dynamic, ongoing basis (e.g., in real-time). In one form,the amount or degree of pre-distortion applied to the LUT samples may bebased on the error between a computed motional branch current and adesired current waveform shape, with the error being determined on asample-by-sample basis. In this way, the pre-distorted LUT samples, whenprocessed through the drive circuit, may result in a motional branchdrive signal having the desired waveform shape (e.g., sinusoidal) foroptimally driving the ultrasonic transducer. In such forms, the LUTwaveform samples will therefore not represent the desired waveform shapeof the drive signal, but rather the waveform shape that is required toultimately produce the desired waveform shape of the motional branchdrive signal when distortion effects are taken into account.

The non-isolated stage 1054 may further comprise an ADC 1078 and an ADC1080 coupled to the output of the power transformer 1056 via respectiveisolation transformers 1082, 1084 for respectively sampling the voltageand current of drive signals output by the generator 1002. In certainforms, the ADCs 1078, 1080 may be configured to sample at high speeds(e.g., 80 MSPS) to enable oversampling of the drive signals. In oneform, for example, the sampling speed of the ADCs 1078, 1080 may enableapproximately 200× (depending on frequency) oversampling of the drivesignals. In certain forms, the sampling operations of the ADC 1078, 1080may be performed by a singe ADC receiving input voltage and currentsignals via a two-way multiplexer. The use of high-speed sampling informs of the generator 1002 may enable, among other things, calculationof the complex current flowing through the motional branch (which may beused in certain forms to implement DDS-based waveform shape controldescribed above), accurate digital filtering of the sampled signals, andcalculation of real power consumption with a high degree of precision.Voltage and current feedback data output by the ADCs 1078, 1080 may bereceived and processed (e.g., FIFO buffering, multiplexing) by the logicdevice 1066 and stored in data memory for subsequent retrieval by, forexample, the DSP processor 1074. As noted above, voltage and currentfeedback data may be used as input to an algorithm for pre-distorting ormodifying LUT waveform samples on a dynamic and ongoing basis. Incertain forms, this may require each stored voltage and current feedbackdata pair to be indexed based on, or otherwise associated with, acorresponding LUT sample that was output by the logic device 1066 whenthe voltage and current feedback data pair was acquired. Synchronizationof the LUT samples and the voltage and current feedback data in thismanner contributes to the correct timing and stability of thepre-distortion algorithm.

In certain forms, the voltage and current feedback data may be used tocontrol the frequency and/or amplitude (e.g., current amplitude) of thedrive signals. In one form, for example, voltage and current feedbackdata may be used to determine impedance phase. The frequency of thedrive signal may then be controlled to minimize or reduce the differencebetween the determined impedance phase and an impedance phase setpoint(e.g., 0°), thereby minimizing or reducing the effects of harmonicdistortion and correspondingly enhancing impedance phase measurementaccuracy. The determination of phase impedance and a frequency controlsignal may be implemented in the DSP processor 1074, for example, withthe frequency control signal being supplied as input to a DDS controlalgorithm implemented by the logic device 1066.

In another form, for example, the current feedback data may be monitoredin order to maintain the current amplitude of the drive signal at acurrent amplitude setpoint. The current amplitude setpoint may bespecified directly or determined indirectly based on specified voltageamplitude and power setpoints. In certain forms, control of the currentamplitude may be implemented by control algorithm, such as, for example,a PID control algorithm, in the processor 1074. Variables controlled bythe control algorithm to suitably control the current amplitude of thedrive signal may include, for example, the scaling of the LUT waveformsamples stored in the logic device 1066 and/or the full-scale outputvoltage of the DAC 1068 (which supplies the input to the power amplifier1062) via a DAC 1086.

The non-isolated stage 1054 may further comprise a second processor 1090for providing, among other things user interface (UI) functionality. Inone form, the UI processor 1090 may comprise an Atmel AT91SAM9263processor having an ARM 926EJ-S core, available from Atmel Corporation,San Jose, Calif., for example. Examples of UI functionality supported bythe UI processor 1090 may include audible and visual user feedback,communication with peripheral devices (e.g., via a Universal Serial Bus(USB) interface), communication with the footswitch 1020, communicationwith an input device 1009 (e.g., a touch screen display) andcommunication with an output device 1047 (e.g., a speaker). The UIprocessor 1090 may communicate with the processor 1074 and the logicdevice 1066 (e.g., via serial peripheral interface (SPI) buses).Although the UI processor 1090 may primarily support UI functionality,it may also coordinate with the DSP processor 1074 to implement hazardmitigation in certain forms. For example, the UI processor 1090 may beprogrammed to monitor various aspects of user input and/or other inputs(e.g., touch screen inputs, footswitch 1020 inputs (FIG. 17),temperature sensor inputs) and may disable the drive output of thegenerator 1002 when an erroneous condition is detected.

In certain forms, both the DSP processor 1074 and the UI processor 1090,for example, may determine and monitor the operating state of thegenerator 1002. For the DSP processor 1074, the operating state of thegenerator 1002 may dictate, for example, which control and/or diagnosticprocesses are implemented by the DSP processor 1074. For the UIprocessor 1090, the operating state of the generator 1002 may dictate,for example, which elements of a user interface (e.g., display screens,sounds) are presented to a user. The respective DSP and UI processors1074, 1090 may independently maintain the current operating state of thegenerator 1002 and recognize and evaluate possible transitions out ofthe current operating state. The DSP processor 1074 may function as themaster in this relationship and determine when transitions betweenoperating states are to occur. The UI processor 1090 may be aware ofvalid transitions between operating states and may confirm if aparticular transition is appropriate. For example, when the DSPprocessor 1074 instructs the UI processor 1090 to transition to aspecific state, the UI processor 1090 may verify that requestedtransition is valid. In the event that a requested transition betweenstates is determined to be invalid by the UI processor 1090, the UIprocessor 1090 may cause the generator 1002 to enter a failure mode.

The non-isolated stage 1054 may further comprise a controller 1096 formonitoring input devices 1045 (e.g., a capacitive touch sensor used forturning the generator 1002 on and off, a capacitive touch screen). Incertain forms, the controller 1096 may comprise at least one processorand/or other controller device in communication with the UI processor1090. In one form, for example, the controller 1096 may comprise aprocessor (e.g., a Mega168 8-bit controller available from Atmel)configured to monitor user input provided via one or more capacitivetouch sensors. In one form, the controller 1096 may comprise a touchscreen controller (e.g., a QT5480 touch screen controller available fromAtmel) to control and manage the acquisition of touch data from acapacitive touch screen.

In certain forms, when the generator 1002 is in a “power off” state, thecontroller 1096 may continue to receive operating power (e.g., via aline from a power supply of the generator 1002, such as the power supply2011 discussed below). In this way, the controller 196 may continue tomonitor an input device 1045 (e.g., a capacitive touch sensor located ona front panel of the generator 1002) for turning the generator 1002 onand off. When the generator 1002 is in the power off state, thecontroller 1096 may wake the power supply (e.g., enable operation of oneor more DC/DC voltage converters 2013 of the power supply 2011) ifactivation of the “on/off” input device 1045 by a user is detected. Thecontroller 1096 may therefore initiate a sequence for transitioning thegenerator 1002 to a “power on” state. Conversely, the controller 1096may initiate a sequence for transitioning the generator 1002 to thepower off state if activation of the “on/off” input device 1045 isdetected when the generator 1002 is in the power on state. In certainforms, for example, the controller 1096 may report activation of the“on/off” input device 1045 to the processor 1090, which in turnimplements the necessary process sequence for transitioning thegenerator 1002 to the power off state. In such forms, the controller 196may have no independent ability for causing the removal of power fromthe generator 1002 after its power on state has been established.

In certain forms, the controller 1096 may cause the generator 1002 toprovide audible or other sensory feedback for alerting the user that apower on or power off sequence has been initiated. Such an alert may beprovided at the beginning of a power on or power off sequence and priorto the commencement of other processes associated with the sequence.

In certain forms, the isolated stage 1052 may comprise an instrumentinterface circuit 1098 to, for example, provide a communicationinterface between a control circuit of a surgical device (e.g., acontrol circuit comprising hand piece switches) and components of thenon-isolated stage 1054, such as, for example, the programmable logicdevice 1066, the DSP processor 1074 and/or the UI processor 190. Theinstrument interface circuit 1098 may exchange information withcomponents of the non-isolated stage 1054 via a communication link thatmaintains a suitable degree of electrical isolation between the stages1052, 1054, such as, for example, an infrared (IR)-based communicationlink. Power may be supplied to the instrument interface circuit 1098using, for example, a low-dropout voltage regulator powered by anisolation transformer driven from the non-isolated stage 1054.

In one form, the instrument interface circuit 198 may comprise a logicdevice 2000 (e.g., logic circuit, programmable logic circuit, PGA, FPGA,PLD) in communication with a signal conditioning circuit 2002. Thesignal conditioning circuit 2002 may be configured to receive a periodicsignal from the logic circuit 2000 (e.g., a 2 kHz square wave) togenerate a bipolar interrogation signal having an identical frequency.The interrogation signal may be generated, for example, using a bipolarcurrent source fed by a differential amplifier. The interrogation signalmay be communicated to a surgical device control circuit (e.g., by usinga conductive pair in a cable that connects the generator 102 to thesurgical device) and monitored to determine a state or configuration ofthe control circuit. The control circuit may comprise a number ofswitches, resistors and/or diodes to modify one or more characteristics(e.g., amplitude, rectification) of the interrogation signal such that astate or configuration of the control circuit is uniquely discernablebased on the one or more characteristics. In one form, for example, thesignal conditioning circuit 2002 may comprises an ADC for generatingsamples of a voltage signal appearing across inputs of the controlcircuit resulting from passage of interrogation signal therethrough. Thelogic device 2000 (or a component of the non-isolated stage 1054) maythen determine the state or configuration of the control circuit basedon the ADC samples.

In one form, the instrument interface circuit 1098 may comprise a firstdata circuit interface 2004 to enable information exchange between thelogic circuit 2000 (or other element of the instrument interface circuit1098) and a first data circuit disposed in or otherwise associated witha surgical device. In certain forms, for example, a first data circuit2006 (FIG. 16A) may be disposed in a cable integrally attached to asurgical device hand piece, or in an adaptor for interfacing a specificsurgical device type or model with the generator 1002. The data circuit2006 may be implemented in any suitable manner and may communicate withthe generator according to any suitable protocol including, for example,as described herein with respect to the circuit 6006. In certain forms,the first data circuit may comprise a non-volatile storage device, suchas an electrically erasable programmable read-only memory (EEPROM)device. In certain forms and referring again to FIG. 19, the first datacircuit interface 2004 may be implemented separately from the logicdevice 2000 and comprise suitable circuitry (e.g., discrete logicdevices, a processor) to enable communication between the programmablelogic device 2000 and the first data circuit. In other forms, the firstdata circuit interface 2004 may be integral with the logic device 2000.

In certain forms, the first data circuit 2006 may store informationpertaining to the particular surgical device with which it isassociated. Such information may include, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. This information may beread by the instrument interface circuit 1098 (e.g., by the logic device2000), transferred to a component of the non-isolated stage 1054 (e.g.,to logic device 1066, DSP processor 1074 and/or UI processor 1090) forpresentation to a user via an output device 1047 and/or for controllinga function or operation of the generator 1002. Additionally, any type ofinformation may be communicated to first data circuit 2006 for storagetherein via the first data circuit interface 2004 (e.g., using the logicdevice 2000). Such information may comprise, for example, an updatednumber of operations in which the surgical device has been used and/ordates and/or times of its usage.

As discussed previously, a surgical instrument may be detachable from ahand piece (e.g., instrument 1024 may be detachable from hand piece1014) to promote instrument interchangeability and/or disposability. Insuch cases, conventional generators may be limited in their ability torecognize particular instrument configurations being used and tooptimize control and diagnostic processes accordingly. The addition ofreadable data circuits to surgical device instruments to address thisissue is problematic from a compatibility standpoint, however. Forexample, designing a surgical device to remain backwardly compatiblewith generators that lack the requisite data reading functionality maybe impractical due to, for example, differing signal schemes, designcomplexity, and cost. Forms of instruments discussed herein addressthese concerns by using data circuits that may be implemented inexisting surgical instruments economically and with minimal designchanges to preserve compatibility of the surgical devices with currentgenerator platforms.

Additionally, forms of the generator 1002 may enable communication withinstrument-based data circuits. For example, the generator 1002 may beconfigured to communicate with a second data circuit 2007 contained inan instrument (e.g., instrument 1024) of a surgical device (FIG. 16A).In some forms, the second data circuit 2007 may be implemented in a manysimilar to that of the data circuit 6006 described herein. Theinstrument interface circuit 1098 may comprise a second data circuitinterface 2010 to enable this communication. In one form, the seconddata circuit interface 2010 may comprise a tri-state digital interface,although other interfaces may also be used. In certain forms, the seconddata circuit may generally be any circuit for transmitting and/orreceiving data. In one form, for example, the second data circuit maystore information pertaining to the particular surgical instrument withwhich it is associated. Such information may include, for example, amodel number, a serial number, a number of operations in which thesurgical instrument has been used, and/or any other type of information.In some forms, the second data circuit 2007 may store information aboutthe electrical and/or ultrasonic properties of an associated transducer1014, end effector 1026, or ultrasonic drive system. For example, thefirst data circuit 2006 may indicate a burn-in frequency slope, asdescribed herein. Additionally or alternatively, any type of informationmay be communicated to second data circuit for storage therein via thesecond data circuit interface 2010 (e.g., using the logic device 2000).Such information may comprise, for example, an updated number ofoperations in which the instrument has been used and/or dates and/ortimes of its usage. In certain forms, the second data circuit maytransmit data acquired by one or more sensors (e.g., an instrument-basedtemperature sensor). In certain forms, the second data circuit mayreceive data from the generator 1002 and provide an indication to a user(e.g., an LED indication or other visible indication) based on thereceived data.

In certain forms, the second data circuit and the second data circuitinterface 2010 may be configured such that communication between thelogic device 2000 and the second data circuit can be effected withoutthe need to provide additional conductors for this purpose (e.g.,dedicated conductors of a cable connecting a hand piece to the generator1002). In one form, for example, information may be communicated to andfrom the second data circuit using a 1-wire bus communication schemeimplemented on existing cabling, such as one of the conductors usedtransmit interrogation signals from the signal conditioning circuit 2002to a control circuit in a hand piece. In this way, design changes ormodifications to the surgical device that might otherwise be necessaryare minimized or reduced. Moreover, because different types ofcommunications implemented over a common physical channel can befrequency-band separated, the presence of a second data circuit may be“invisible” to generators that do not have the requisite data readingfunctionality, thus enabling backward compatibility of the surgicaldevice instrument.

In certain forms, the isolated stage 1052 may comprise at least oneblocking capacitor 2096-1 connected to the drive signal output 1060 b toprevent passage of DC current to a patient. A single blocking capacitormay be required to comply with medical regulations or standards, forexample. While failure in single-capacitor designs is relativelyuncommon, such failure may nonetheless have negative consequences. Inone form, a second blocking capacitor 2096-2 may be provided in serieswith the blocking capacitor 2096-1, with current leakage from a pointbetween the blocking capacitors 2096-1, 2096-2 being monitored by, forexample, an ADC 2098 for sampling a voltage induced by leakage current.The samples may be received by the logic circuit 2000, for example.Based changes in the leakage current (as indicated by the voltagesamples in the form of FIG. 19), the generator 1002 may determine whenat least one of the blocking capacitors 2096-1, 2096-2 has failed.Accordingly, the form of FIG. 19 provides a benefit oversingle-capacitor designs having a single point of failure.

In certain forms, the non-isolated stage 1054 may comprise a powersupply 2011 for outputting DC power at a suitable voltage and current.The power supply may comprise, for example, a 400 W power supply foroutputting a 48 VDC system voltage. The power supply 2011 may furthercomprise one or more DC/DC voltage converters 2013 for receiving theoutput of the power supply to generate DC outputs at the voltages andcurrents required by the various components of the generator 1002. Asdiscussed above in connection with the controller 1096, one or more ofthe DC/DC voltage converters 2013 may receive an input from thecontroller 1096 when activation of the “on/off” input device 1045 by auser is detected by the controller 1096 to enable operation of, or wake,the DC/DC voltage converters 2013.

Having described operational details of various forms of the surgicalsystems 19 (FIG. 1), 190 (FIG. 10), 1000 (FIG. 16) operations for theabove surgical systems 19, 190, 1000 may be further described generallyin terms of a process for cutting and coagulating tissue employing asurgical instrument comprising an input device 406, 1045 and thegenerator 1002. Although a particular process is described in connectionwith the operational details, it can be appreciated that the processmerely provides an example of how the general functionality describedherein can be implemented by any one of the surgical systems 19, 190,1000. Further, the given process does not necessarily have to beexecuted in the order presented herein unless otherwise indicated. Aspreviously discussed, any one the input devices 406, 1045 may beemployed to program the output (e.g., impedance, current, voltage,frequency) of the surgical devices 100 (FIG. 1), 120 (FIG. 10), 1002(FIG. 16), 1006 (FIG. 16).

FIGS. 20-22 illustrate various forms of logic flow diagrams of 1200,1300, 1400 related to a tissue algorithm for detecting when rapidheating of the ultrasonic end effector 1026 blade occurs and provide theopportunity for generating visual, audible and/or tactile feedbackand/or changing an operational mode of the instrument and/or generator.For example, feedback may be provided via the output indicator 412(FIGS. 9, 11) and/or the output device 1047 (FIG. 16) (e.g.,annunciation, modulation of power output and/or display of content).According to the present disclosure, when multiple reference numbers areused to described an element such as “ultrasonic surgical instrument100, 120, 1004,” it should be understood to reference any one of theelements, such as, for example, “ultrasonic surgical instrument 100,” or“ultrasonic surgical instrument 120,” or “ultrasonic surgical instrument1004.” It will be appreciated however, that any of the algorithmsdescribed herein are suitable for execution with any of the instruments100, 120, 1004 described herein.

In various forms, feedback may be provided by the output indicator 412shown in FIGS. 9 and 11 or the output device 1047 in FIG. 16. Thesefeedback devices (e.g., output indicator 412, output device 1047) areparticularly useful in applications where the tissue being manipulatedby the end effector 81 (FIG. 1), 810 (FIG. 10), 1026 (FIG. 16) is out ofthe user's field of view and the user cannot see when a change of stateoccurs in the tissue. The feedback device communicates to the user thata change in tissue state has occurred as determined in accordance withthe operations described with respect to the logic flow diagrams 700,800, 900, 1200, 1300, 1400 as they relate to corresponding tissuealgorithms. The feedback devices may be configured to provide varioustypes of feedback according to the current state or condition of thetissue. A change of state of the tissue may be determined based ontransducer and/or tissue measurements based on voltage, current, andfrequency measurements in accordance with the operations described, forexample, with respect to the logic flow diagrams 700, 800, 900 describedabove in connection with FIGS. 15A-C and the logic flow diagrams 1200,1300, 1400 described below in connection with FIGS. 20-22, as well asthe various other logic flow diagrams described herein

In one form, the logic flow diagrams 1200, 1300, 1400 may be implementedas executable modules (e.g., algorithms) comprising computer readableinstructions to be executed by the processor 400 (FIGS. 9, 11, 14)portion of the generator 30, 500 or the generator 1002 (FIGS. 16, 17,19). In various forms, the operations described with respect to thelogic flow diagrams 1200, 1300, 1400 may be implemented as one or morethan one software component, e.g., program, subroutine, logic; one ormore than one hardware components, e.g., processor, DSP, PLD, PGA, FPGA,ASIC, circuit, logic circuit, register; and/or combinations of softwareand hardware. In one form, the executable instructions to perform theoperations described by the logic flow diagrams 1200, 1300, 1400 may bestored in memory. When executed, the instructions cause the processor400, the DSP processor 1074 (FIG. 19) or logic device 1066 (FIG. 19) todetermine a change in tissue state in accordance with the operationsdescribed in the logic flow diagrams 1200, 1300, and 1400 and providefeedback to the user by way of the output indicator 412 (FIGS. 9, 11) oroutput indicator 1047 (FIGS. 16, 17). In accordance with such executableinstructions, the processor 400, DSP processor 1074, and/or logic device1066 monitors and evaluates the voltage, current, and/or frequencysignal samples available from the generator 30, 500, 1002 and accordingto the evaluation of such signal samples determines whether a change intissue state has occurred. As further described below, a change intissue state may be determined based on the type of ultrasonicinstrument and the power level that the instrument is energized at. Inresponse to the feedback, the operational mode of any one of theultrasonic surgical instruments 100, 120, 1004 may be controlled by theuser or may be automatically or semi-automatically controlled.

A brief summary of a tissue algorithm represented by way of the logicflow diagrams 1200, 1300, 1400 will now be described in connection withany one of the ultrasonic surgical instruments 100, 120, 1004 driven bya corresponding generator 30 (FIG. 1), 500 (FIG. 10), 1002 (FIG. 17). Inone aspect, the tissue algorithm detects when the temperature of theblade portion (and therefore resonance) of the ultrasonic end effector81 (FIG. 1), 810 (FIG. 10), 1026 (FIG. 17) is changing rapidly (of mostinterest is an increasing change). For a clamping or shears typeinstrument, this change may correspond to a common clinical scenario,among others, when minimal-to-no tissue, tissue debris or fluid isadjacent the blade and the blade is activated against the clamp arm,clamp pad or other suitable tissue biasing member. For non-clampingapplications where an instrument with or without a clamp arm andassociated mechanisms is used to effect tissue, this change correspondsto conditions where rapid heating occurs such as when the blade isactivated against bone or other hard materials or when excessive forceis used to couple the blade to tissue targets. These are illustrativecases; one can imagine other clinical scenarios where rapid bladeheating may occur and such a tissue algorithm as described here is ofbenefit.

The tissue algorithm represented by the logic flow diagrams 1200, 1300,1400 and any of the algorithms described herein may be employed inconjunction with any of the generators 30, 500, 1002 described herein,and other suitable generators such as the GEN 04, GEN 11 generatorsavailable from Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio, andrelated devices, systems, that may leverage the algorithm or technologydisclosed herein. Accordingly, in the description of the tissuealgorithm in conjunction with the flow diagrams 1200, 1300, 1400reference is made to the generators 30, 500, 1002 described inconnection with corresponding FIGS. 1-9, 10-13, and 16-19.

Accordingly, with reference now to FIGS. 1-14, the frequency of theblade/hand piece resonant system of any one of the ultrasonic surgicalinstruments 100, 120, 1004 is dependent on temperature. When, forexample, an ultrasonic shear type end effector cuts through a clampedpiece of tissue, the blade heats and thins the tissue until ultimatelyit cuts through the tissue. At this point, the blade resides against thetissue pad and, if clamp pressure remains between the two, the blade andpad interface will draw power via the mechanical or vibratory motion ofthe blade relative to the pad. The power “deposited” at the interfacewill be largely conducted into the blade tip as the pad material isquite insulative. It is this thermal energy that alters the stiffness ofthe blade tip and the system resonance will change accordingly due tothese localized (to the tip) conditions. The generator 30, 500, 1002tracks this resonance. The shears example illustrates one scenario forwhich the algorithm is of use. Additional scenarios are back-cuttingwith a shears device with the clamp arm closed, blade cutting againsttough or hard tissue, or any scenario in which knowing the thermalcondition of the blade end-effector is desired. A tissue algorithm thatapplies logic to this tracking of resonance and, therefore, blade tipthermal condition is now described in connection with logic flowdiagrams 1200, 1300, 1400 in FIGS. 20-22.

In addition, the description of the tissue algorithm described inconnection with logic flow diagrams 1200, 1300, 1400 will be accompaniedwith illustrative examples via data obtained using any one of theultrasonic surgical instruments 100, 120, 1004 comprising acorresponding generator 30, 500, 1002 described herein.

The tissue algorithm described in connection with logic flow diagrams1200, 1300, 1400 relies on the monitoring of electrical drive signals,especially those correlating to the resonant frequency of the drivesignal. The algorithm monitors the resonant frequency and its changewith time (i.e., the first derivative of frequency with respect totime). Throughout this disclosure, this change in frequency with time isreferred to as frequency slope. Frequency slope is calculated locally(from a time perspective) by calculating the change in frequency ofadjacent (or relatively near) data points and dividing by thecorresponding change in time. Because of signal transients, averaging orany of a multitude of applicable filtering or smoothing techniques (suchthat trends are more easily discernable and prevents turning on/offcondition sets rapidly) may be employed. The data plots shown in FIGS.62, 63, 64 illustrate the calculation of frequency slope and the use ofaveraging techniques (e.g., exponentially weighted moving average orEWMA) to obtain frequency slope values useful for control/monitoring.Other descriptions of frequency slope include, without limitation,“first derivative of frequency” and “frequency change with respect totime.”

FIG. 20 is a logic flow diagram 1200 of a tissue algorithm that may beimplemented in one form of a generator 30, 500, 1002 and/or an onboardgenerator or control circuit of an instrument. At a general level, thetissue algorithm described in connection with logic flow diagram 1200assesses the electrical signals in real time against a set of logicconditions that correlate to events of interest (e.g., blade ofultrasonic instrument is rapidly heating). Accordingly, the generator30, 500, 1002 determines when a set of logic conditions occur andtriggers a corresponding set of responses. The terms “Condition Set” and“Response set” are defined follows:

(1) Condition Set—a set of logic conditions that electrical signals aremonitored against in real time.

(2) Response Set—one or more responses of the generator 30, 500, 1002system to a Condition Set having been met.

At 1202, the generator 30, 500, 1002 is placed in an ultrasonic drivemode in a ready state.

At 1204, the generator 30, 500, 1002 is activated at a predeterminedpower level N. When the user activates the surgical system 19, 190,1000, the corresponding generator 30, 500, 1002 responds by seeking thesurgical system 19, 190, 1000 resonance and then ramping the output tothe end effectors 81, 810, 1026 to the targeted levels for the commandedpower level.

At 1206, the tissue algorithm determines whether parameters associatedwith the tissue algorithm are in use by determining when at least oneCondition Sets/Response Sets flag is enabled. When no such flags areenabled, the algorithm proceeds along “NO” path where at 1208 thesurgical system 19, 190, 1000 is operated in normal ultrasonic mode andat 1210, the corresponding generator 30, 500, 1002 is deactivated whenthe tissue procedure is completed.

When at least one flag for setting Condition Sets/Response Sets isenabled, the algorithm proceeds along “YES” path and the generator 30,500, 1002 utilizes the tissue algorithm 1300 signal evaluation afterresetting a Timer X and Timer X latch. The tissue algorithm 1300,described in more detail below, may return an indication of whether agiven Condition Set is currently met or “true.” In one form, the atleast one flag for setting Condition Sets/Response Sets may be stored inan EEPROM image of an instrument 100, 120, 1004 attached to therespective generator 30, 500, 1002. The EEPROM flags for setting theCondition Sets/Response Sets to an enabled state are contained in TABLE1.

TABLE 1 Value to En- Value able for “Nor- Enable/Disable Flag Functionsfor Tissue Algorithm Func- mal” Name Description tion Drive ConditionSet 1 If Condition Set 1 is met and this 1 0 Pulsing flag function isenabled, the generator pulses power per the pulsing parameters as a partof Response Set 1 Condition Set 1 If Condition Set 1 is met and this 1 0LCD display function is enabled, the generator flag LCD displays anassigned graphics screen as part of Response Set 1 Condition Set 1 IfCondition Set 1 is met and this 1 0 Audio flag function is enabled, thegenerator plays an assigned audio file as part of Response Set 1Condition Set 2 If Condition Set 2 is met and this 1 0 Pulsing flagfunction is enabled, the generator pulses power per the pulsingparameters as a part of Response Set 2 Condition Set 2 If Condition Set2 is met and this 1 0 LCD display function is enabled, the generatorflag LCD displays an assigned graphics screen as part of Response Set 2Condition Set 2 If Condition Set 2 is met and this 1 0 Audio flagfunction is enabled, the generator plays an assigned audio file as partof Response Set 2

In one form, the tissue algorithm 1300 signal evaluation portion of thelogic flow diagram 1200 utilizes two Condition Sets and each of thesetwo Conditions Sets has a Response Set, which are described in moredetail in connection with logic flow diagrams 1300, 1400. The tissuealgorithm 1300 logic may be illustrated as follows: when Condition Set 1is met, Response Set 1 is triggered. Having two condition sets enables ahierarchical response (differentiated responses based upon conditionlevel) and also provides the ability to manage a complicated series ofevents.

At 1210, responses for Condition Sets that are met are triggered. Loop1212 is repeated until the Condition Sets are met and the generator 30,500, 1002 is deactivated at 1214.

The pulsing response is more detailed and requires further explanationthan the relatively simple audio and LCD display responses. When apulsing response is triggered, the generator 30, 500, 1002 drives apulsed output as defined by the by the following four parameters:

(1) First Pulse Amplitude (EEPROM parameter, one value for each powerlevel)—the drive amplitude for the first pulse;

(2) First Pulse Time (EEPROM parameter)—the time over which the firstpulse amplitude is driven;

(3) Second Pulse Amplitude (EEPROM parameter, one value for each powerlevel)—the drive amplitude for the second pulse; and

(4) Second Pulse Time (EEPROM parameter)—the time over which the secondpulse amplitude is driven.

In certain forms, the First Pulse Amplitude and Second Pulse Amplitudemay increase, decrease or stay the same relative to one another. Forexample, in certain forms, the First Pulse Amplitude and Second PulseAmplitude may be equal. Also, in certain forms, the First Pulse TimePeriod and Second Pulse Time Period may take any suitable valuesincluding, for example, fractions of a second, minutes, hours, etc. Inone example form, the First Pulse Time Period and the Second Pulse TimePeriod may be 55 seconds.

When driving a pulsed output, the generator 30, 500, 1002 drives thefirst pulse, then the second pulse and then repeats. The pulse amplitudemay be expressed in units of: percentage of the commanded power level'soutput current. The commanded power level may be set by the activationswitch (MIN or MAX) and the generator setting when MIN is activated.

FIG. 21 is a logic flow diagram 1300 of a signal evaluation tissuealgorithm portion of the tissue algorithm shown in FIG. 20 that may beimplemented in one form of a generator. The tissue algorithm 1300 maydetermine whether one or more Condition Sets are met (and, therefore,whether corresponding Response Sets should be triggered at 1210). Thetissue algorithm signal evaluation flow shown in FIG. 21 shows theapplication of a “time to wait” parameter 1304 and the calculation of afrequency slope (also referred to as local frequency slope because it isa running calculation).

At 1302, the algorithm calculates the time since activation wasinitiated at 1204 (FIG. 20). This time is expressed as T_(Elapse), whichis T_(System)−T_(PowerOn). As previously discussed, when the useractivates the surgical system 19, 190, 1000, the corresponding generator30, 500, 1002 responds by seeking the resonance of the ultrasonic system100, 120, 1004 and then ramping the output to the corresponding endeffectors 81, 810, 1026 to the targeted levels for the commanded powerlevel.

During this time, the associated signal transients can make theapplication of algorithm logic difficult. The algorithm, therefore,utilizes the “time to wait” parameter 1304 that is stored in the EEPROMimage located in a hand piece portion of the ultrasonic surgicalinstrument 100, 120, 1004. The “time to wait” parameter 1304 (EEPROMparameter) is defined as the time at the beginning of an activationduring which the generator 30, 500, 1002 does not apply the tissuealgorithm to lessen the influence of resonance seek and drive rampsignal transients on algorithm logic. A typical “time to wait” parameter1304 value is about 0.050 to 0.600 seconds (50 to 600 msec).

At 1306, T_(Elapse) is compared to the “time to wait” parameter 1304value. When T_(Elapse) is less than or equal to the “time to wait”parameter 1304 value, the algorithm proceeds along “NO” path tocalculate at 1302 a new T_(Elapse). When T_(Elapse) is greater than the“time to wait” parameter 1304 value, the algorithm proceeds along “YES”path to evaluate the signal.

At 1308, the algorithm performs the Signal Evaluation/Monitoringfunction. As previously stated, one aspect of the function algorithm isto monitor frequency slope. In a physical sense, frequency slopecorrelates to heat flux into or out of the resonant system comprisingthe blade and the hand piece acoustical subassembly, such as theultrasonic systems 100, 120, 1004 disclosed herein. The changes infrequency and frequency slope during activation on tissue are dominatedby the changing conditions occurring at the end-effector (tissue dryingout, separating and blade contacting the clamp arm pad). When the bladeis being heated (i.e., heat flux into the blade), the frequency slope isnegative. When the blade is being cooled (i.e., heat flux out of theblade), the frequency slope is positive. Accordingly, the algorithmcalculates the slope between frequency data points, i.e., incomingfrequency data points 1310 (F_(t)) and previous F_(t) data points 1312.The calculated frequency slope also may be referred to as a localfrequency slope because it is a running calculation. The local frequencyslope may be referred to as F_(Slope_Freq), F_(t), which is thefrequency slope (F_(Slope_Freq)) at the resonance frequency (F_(t)). Thelocal frequency slope may be routed to a Condition Set 1, Condition Set2 1400, for example, for evaluation in accordance with the flow diagram1400 shown in FIG. 22. Although two Condition Sets are shown, it will beappreciated that additional Condition Sets may be added in some exampleforms.

FIG. 22 is a logic flow diagram 1400 for evaluating condition sets forthe signal evaluation tissue algorithm shown in FIG. 21 that may beimplemented in one form of a generator, such as 30, 50, 1002. The logicflow diagram 1400 evaluates Condition Set X, where X is either 1 or 2,for example.

In accordance with the tissue algorithm, at 1402, the local frequencyslope calculated at 1308 (FIG. 21) is compared against a frequency slopethreshold parameter 1404 value for Condition Set X at Power Level N. Thefrequency slope threshold parameters 1404 may be stored in an EEPROMlocated in the attached instrument 100, 120, 1004, where one EEPROMparameter value is stored for each power level. When the local frequencyslope calculated at 1308 drops below the frequency slope thresholdparameter 1404 value, a first Response Set may be triggered at 1210(FIG. 20). When the blade is being heated at a relatively rapid rate,the frequency slope will become more negative and the tissue algorithmidentifies this condition by way of the frequency slope dropping belowthe frequency slope threshold parameter 1404 value. Again, the frequencyslope indicates the rate of thermal change or heat flux into or out ofthe blade.

In accordance with the tissue algorithm, also at 1402, the resonantfrequency is compared against a frequency threshold parameter 1406 valuefor Condition set X. The frequency threshold parameter 1406 value may bestored in an EEPROM located in the attached instrument 100, 120, 1004.When the resonant frequency drops below the threshold frequencyparameter 1406 value, a second Response Set may be triggered at 1210(FIG. 20). As a blade is continually heated, the frequency will continueto drop. A frequency threshold parameter 1406 value is intended toimprove algorithm robustness by providing additional information aboutthe thermal condition of the blade (in addition to the more dynamicindicator, the frequency slope). Frequency drop from some knowncondition such as room temperature gives a good indication of thethermal state of the resonant system relative to these known thermalconditions.

In some forms, frequency slope and resonant frequency may be utilized ina common Condition Set. For example, a Condition Set may not be metunless the frequency slope and resonant frequency both meet giventhresholds. For example, at 1402, when the frequency slope(F_(Slope_Freq)) is less than the frequency slope threshold parameter1404 value and the resonant frequency (F_(t)) is less than the frequencythreshold parameter 1406 value, the algorithm proceeds along “YES” pathto 1408 to increment a Timer X (where X corresponds to the particularCondition Set being evaluated by the tissue algorithm).

In comparing the electrical signals, e.g., the frequency slope(F_(Slope_Freq)) and the resonant frequency (F_(t)), against respectivethresholds parameters 1404, 1406, borderline conditions where the signalbounces back-and-forth across the threshold can be taken intoconsideration as follows. In one aspect, the tissue algorithm employs a“required time before trigger” parameter 1412 value (which also may bestored in the instrument EEPROM) for the particular Condition Set X toaccount for this consideration. The “required time before trigger”parameter 1412 value is defined as the time required before trigger(EEPROM parameter)—required time for frequency slope and/or frequency tobe less than their respective thresholds for a Response Set to betriggered. This is intended to prevent rapid “back and forth” triggeringof a response. It may be useful, however, to track non-rapid “back andforth” triggering, which may occur.

Thus, at 1414 the algorithm determines whether the Timer X value isgreater than the “required time before trigger” parameter 1412 value forCondition Set X. When the Timer X value is greater than the “requiredtime before trigger” parameter 1412 value, the algorithm proceeds along“YES” path to set a latch for Condition Set X at 1416. Output 1418indicates that the Condition Set X is met. When the Timer X value isless than or equal to the “required time before trigger” parameter 1412value, the algorithm proceeds along “NO” path to indicate at output 1420that the Condition Set X is not met.

At 1402, when either the frequency slope (F_(Slope_Freq)) is greaterthan or equal to the frequency slope threshold parameter 1404 value orthe resonant frequency (F_(t)) is greater than then or equal to thefrequency threshold parameter 1406 value, the algorithm proceeds along“NO” path to reset the Timer X at 1410 (where X corresponds to theparticular Condition Set being evaluated by the tissue algorithm).

For additional robustness, two latching parameters are employed by thealgorithm. Without the use of latching, the algorithm is configured toend a response set when either (a) the system is deactivated or (b) whenthe signal or signals are no longer below their respective thresholds.Two latching parameters can be utilized. They are a “minimum latch time”parameter 1422 and a “cross-back frequency slope threshold” parameter1424. These latch parameters 1422, 1424 are important for robustnessaround: (a) clamp arm pad surfaces that become more lubricious withelevated temperature and (b) pulsing output where signal transients atthe pulse transitions are expected.

The minimum latch time parameter 1422 (EEPROM parameter) can be definedas the minimum amount of time for response(s) to a Condition Set X to betriggered. Considerations for minimum latch time include: (a) the lengthof time required to play a triggered audible response (e.g., in oneform, a “pre-alert” WAV audio file may be about 0.5 seconds long), (b)the typical (about 0.5 to 1.0 sec) or extreme (about 1.5 to 2.0 sec)user response times for an event, or (c) the typical tissue re-grasptime for a multi-cut (known as “marching”) application (about 1.1-2.0seconds with a mean of about 1.6 seconds).

The cross-back frequency slope threshold parameter 1424 (EEPROMparameter) can be defined as the frequency slope threshold above which atriggered response stops (i.e., is no longer triggered). This providesfor a higher “cross-back-over” frequency slope threshold that is taskedwith distinguishing between activating against the pad and jaw opened(versus distinguishing between activating on tissue and activating onthe pad).

In accordance with the tissue algorithm portion represented by logicflow diagram 1400, after the Timer X is reset at 1410, at 1426, thetissue algorithm determines whether either the latch for Condition Set Xor the Cross-back Frequency Slope Latch is set. When both latches arenot set, the algorithm proceeds along “NO” to indicate at output 1420that the Condition Set X is not met. When either one of the latches isset, the algorithm proceeds along “YES” path to 1428.

At 1428, the algorithm determines whether the Latched Time for ConditionSet X is greater than the minimum latch time parameter 1422 value forCondition Set X and whether the frequency slope (F_(Slope_Freq)) isgreater than the cross-back frequency slope threshold parameter 1424value the algorithm proceeds along “YES” path to reset the Latch forTimer X at 1430 and to indicate at output 1420 that the Condition Set Xis not met. When the Latched Time for Condition Set X is less than orequal to the minimum latch time parameter 1422 value for Condition Set Xand the frequency slope (F_(Slope_Freq)) is less than or equal to thecross-back frequency slope threshold parameter 1424 value the algorithmproceeds along “NO” path to indicate at output 1432 that the ConditionSet X is met.

As shown in FIGS. 21 and 22, there are two identical Condition Sets 1and 2 from a flow perspective. These Conditions Sets 1 and 2 havereplicate sets of parameters as contained in TABLE 2. Algorithmparameters that are shared by the Condition Sets 1 and 2 are containedin TABLE 3.

TABLE 2 contains a summary of the replicated algorithm EEPROM parametersfor each of the Condition Sets and the number parameters per ConditionSet.

TABLE 2 Algorithm EEPROM Parameter Summary, Replicated Parameters forEach of the Condition Sets # of Parameters Replicated Parameters forEach of the Condition Sets per Condition Set Required time beforetriggered 1 Minimum latch time 1 Frequency Slope Thresholds (one foreach power 5 level) Frequency Threshold 1

TABLE 3 contains a summary of the shared algorithm EEPROM parameters foreach of the Condition Sets (not replicated) and the number parameters.

TABLE 3 Algorithm EEPROM Parameter Summary, Common Parameters to allCondition Sets Parameters Shared by Condition Sets (not replicated) # ofParameters Time to wait 1 Cross-back Frequency Slope Threshold 1 FirstPulse Amplitudes (one for each power 5 level) First Pulse Time 1 SecondPulse Amplitudes (one for each power 5 level) Second Pulse Time 1

For clarity of disclosure, the tissue algorithm described in connectionwith the logic flow diagrams 1200, 1300, 1400 shown in respective FIGS.20-22 will now be described in terms of four examples. The basicapplication of the tissue algorithm includes the monitoring of frequencyslope, resonant frequency, or both against their respective thresholds.Accordingly, a first example includes the monitoring of frequency slopeagainst its respective threshold and is illustrated in FIGS. 23-28. Asecond example includes the monitoring of resonant frequency against itsrespective threshold and is illustrated in FIGS. 29-31. A third exampleincludes the monitoring both the frequency slope and the resonantfrequency, against their respective threshold and is illustrated inFIGS. 32-34. Finally, a fourth example also includes the monitoring bothof the frequency slope and the resonant frequency, against theirrespective threshold.

Example 1: Monitoring Frequency Slope Against Respective Threshold

A first example case includes the monitoring of frequency slope againsta respective threshold is illustrated with reference to FIGS. 23-28. Thefirst example, and most simple, is the example of triggering a ResponseSet based only on the frequency slope. TABLE 4 contains representativeparameters for this objective for surgical instruments such as any oneof the surgical instruments 19, 190, 1000 disclosed herein comprising acorresponding ultrasonic instrument such as ultrasonic instruments 100,120, 1004 disclosed herein.

TABLE 4 Representative Parameters for Triggering an Audio Indication byFrequency Slope Threshold Only (one Condition Set utilized) ParameterValue* Condition Set 1 Pulsing flag 0 Condition Set 1 LCD display flag 0Condition Set 1 Audio flag 1 Required time before triggered, Condition50 msec Set 1 Minimum latch time, Condition Set 1 0 msec* FrequencySlope Thresholds (one for each level 5: −0.060 kHz/sec power level),Condition Set 1 level 4: −0.053 kHz/sec level 3: −0.045 kHz/sec level 2:−0.038 kHz/sec level 1: −0.030 kHz/sec Frequency Threshold, ConditionSet 1 56,000 Hz* Time to wait 100 msec Cross-back Frequency SlopeThreshold −0.020 kHz/sec First Pulse Amplitudes (one for each power N/Alevel) First Pulse Time N/A Second Pulse Amplitudes (one for each powerN/A level) Second Pulse Time N/A *These parameter values are set to anappropriate extreme such that they do not effectively take part in thelogic flow (e.g., set to always be “true”).

FIGS. 23-25 show signal data produced by a generator with therepresentative/illustrative parameters contained in TABLE 4. Thegenerator may be similar to any one of the generators 30, 500, 1002disclosed herein, which forms a portion of the respective surgicalsystems 19, 190, 1000 operating in ultrasonic mode (e.g., ultrasonicsystem 19, 190, 1000) applied on tissue in accordance with the presentdisclosure.

The use of only the frequency slope to trigger a Response Set may befurther demonstrated in the “burn-in” scenario or test. FIGS. 26-28 showsignal data produced by a generator with the representative/illustrativeparameters contained in TABLE 4 during a “burn-in” scenario or test. A“burn-in” simulates the use case where a user activates a shears typeultrasonic surgical instrument without intervening tissue (e.g.,back-cutting with jaws closed). This test also may be useful forquantifying device characteristics, such as, for example, “responsetime.”

The response time of an ultrasonic instrument may be defined as the timerequired for an ultrasonic system (instrument, hand piece, and generatorwith tissue algorithm) to respond to the clamp arm pad coming intocontact with the blade. The ultrasonic system is usually initiallyactivated “in-air” (i.e., unloaded), the clamp arm is closed against theblade and held for a period of time and then the clamp arm is opened andthe ultrasonic system is deactivated. The response time is the timebetween the point at which the quiescent power (power in-air) begins tochange due to the clamp arm pad initiating contact with the blade andthe point at which the Response Set is triggered. This is also a testthat enables quantification of the rate of cooling—the higher the rateof cooling (assuming similar convective boundary conditions) the morethermal energy or residual heat there is in the blade. The rate ofcooling is proportional to the frequency slope (to reinforce: a positivefrequency slope value correlates to the instantaneous heat flux out ofthe blade). As will be detailed later, the rate of cooling also may bemonitored and used for control purposes so that, for example, if therate of cooling as defined by a positive frequency slope is greater thana threshold value, one knows that the blade is “carrying” a large amountof thermal energy and is dissipating it rapidly.

FIG. 23A is a graphical representation 1500 of frequency slope versustime of a waveform 1502 of one form of a generator during a typicaltissue cut. Frequency slope (kHz/sec) is shown along the vertical axisand time (Sec) is shown along the horizontal axis for a typical tissuecut using any one of the ultrasonic systems comprising correspondingultrasonic surgical instruments set on power level 5. The frequencyslope threshold 1504 used for this application was −0.06 kHz/sec and isshown by the horizontal dashed line. The vertical dash-dot line 1506shows the time (2.32 seconds) that the tissue began to separate, and thevertical dashed line 1508 shows the time (2.55 seconds) at which theultrasonic system triggered a Response Set (in this case, per TABLE 4,an audible sound only).

FIG. 23B is a graphical representation of a second time derivative offrequency (slope of frequency slope) versus time waveform 1503 (shown indashed line) superimposed over the waveform 1502 shown in FIG. 23 of oneform of a generator during a typical tissue cut.

FIG. 24 is a graphical representation 1510 of frequency versus timewaveform 1512 of one form of a generator during a typical tissue cut asit relates to the graphical representation 1500 shown in FIG. 23A.Resonant frequency (kHz) is shown along the vertical axis and time (Sec)is shown along the horizontal axis for the typical tissue cut using anyone of the ultrasonic systems set on power level 5. The verticaldash-dot line 1506 shows the time (2.32 seconds) that the tissue beganto separate, and the vertical dashed line 1508 shows the time (2.55seconds) at which the ultrasonic system triggered a Response Set (inthis case, an audible sound only).

FIG. 25 is a graphical representation 1514 of power consumption versustime waveform 1514 of one form of a generator during a typical tissuecut as it relates to the graphical representation 1500 shown in FIG.23A. Power (W) is shown along the vertical axis and time (Sec) is shownalong the horizontal axis for the typical tissue cut using any one ofthe ultrasonic systems set on power level 5. The vertical dash-dot line1506 shows the time (2.32 seconds) that the tissue began to separate,and the vertical dashed line 1508 shows the time (2.55 seconds) at whichthe ultrasonic system triggered a Response Set (in this case, an audiblesound only).

FIG. 26 is a graphical representation 1516 of frequency slope versustime waveform 1518 of one form of a generator during a burn-in test. Theparameters for this test are consistent with those contained in TABLE 4.Frequency slope (kHz/sec) is shown along the vertical axis and time(Sec) is shown along the horizontal axis for a typical tissue cut usingany one of the ultrasonic systems set on power level 5. The frequencyslope threshold 1504 used for this application was −0.06 kHz/sec as isshown by the horizontal dashed line. The vertical dotted line 1524 showsthe point in time (2.49 seconds) that the quiescent power begins tochange due to clamping, the vertical dash-dot line 1506 shows the time(2.66 seconds) at which power has completed ramp-up, and the verticaldashed line 1508 shows the time (2.72 seconds) that the ultrasonicsystem triggered a Response Set (in this case, an audible sound only).As shown in the graphical representation 1516, the frequency slope at1520 correlates to the rate of cooling or heat flux out of the blade.Also, the response time 1522 of the ultrasonic system is measured as thetime lapse between the point in time (2.49 seconds) that the quiescentpower begins to change due to clamping and the time (2.72 seconds) thatthe ultrasonic system triggered a Response Set.

FIG. 27 is a graphical representation 1524 of a frequency versus timewaveform 1526 of one form of a generator during a burn-in test as itrelates to the graphical representation 1516 shown in FIG. 26. Resonantfrequency (kHz) is shown along the vertical axis and time (Sec) is shownalong the horizontal axis for the typical tissue cut using any one ofthe ultrasonic systems set on power level 5.

FIG. 28 is a graphical representation 1528 of a power consumption versustime waveform 1530 of one form of a generator during a burn-in test asit relates to the graphical representation 1516 shown in FIG. 26. Power(W) is shown along the vertical axis and time (Sec) is shown along thehorizontal axis for the typical tissue cut using any one of theultrasonic systems set on power level 5.

Example 2: Triggering a Response Set Based Only on the FrequencyThreshold

A second example case includes triggering a Response Set based only onthe frequency threshold with reference to FIGS. 29-35. TABLE 5 containsrepresentative parameters for this objective in connection with surgicalinstruments such as any one of the surgical instruments 19, 190, 1000disclosed herein comprising corresponding ultrasonic instruments such asthe ultrasonic instrument 100, 120, 1004 disclosed herein. It will beappreciated that triggering via frequency threshold may be of limitedutility as it is less indicative of dynamic end-effector conditions andis presented herein for completeness of disclosure. The inclusion offrequency slope in the tissue algorithm discussed in connection withlogic flow diagrams 1200, 1300, 1400 is intended for use in combinationlogic (combined with use of the frequency slope threshold) which iscovered in the next section of this specification.

TABLE 5 Representative Parameters for Triggering an Audio Indication byFrequency Threshold Only (one Condition Set utilized) Parameter Value*Condition Set 1 Pulsing flag 0 Condition Set 1 LCD display flag 0Condition Set 1 Audio flag 1 Required time before triggered, Condition50 msec Set 1 Minimum latch time, Condition Set 1 0 msec* FrequencySlope Thresholds (one for each level 5: 1.00 kHz/sec* power level),Condition Set 1 level 4: 1.00 kHz/sec* level 3: 1.00 kHz/sec* level 2:1.00 kHz/sec* level 1: 1.00 kHz/sec* Frequency Threshold, Condition Set1 55,100 Hz Time to wait 100 msec Cross-back Frequency Slope Threshold−1.00 kHz/sec* First Pulse Amplitudes (one for each power N/A level)First Pulse Time N/A Second Pulse Amplitudes (one for each N/A powerlevel) Second Pulse Time N/A *These parameter values are set to anappropriate extreme such that they do not effectively take part in logicflow (e.g., set to always be “true”)

FIGS. 29-34 show waveforms produced by a generator with therepresentative/illustrative parameters contained in TABLE 5. Thegenerator may be similar to any one of the generators 30, 500, 1002disclosed herein, which forms a portion of the respective surgicalsystems 19, 190, 1000 operating in ultrasonic mode (e.g., ultrasonicsystem 19, 190, 1000) applied on tissue in accordance with the presentdisclosure.

The selection of 55,100 Hz as the frequency threshold in TABLE 5 wasbased on test data for two abuse cases: (1) where an ultrasonicinstrument is activated against the tissue pad for a prolonged period oftime; and (2) where an ultrasonic instrument is used to make 10successive cuts on excised porcine jejunum tissue as quickly as possiblewhile keeping the generator running throughout. Each of these two abusecases will be discussed in more detail with reference to respective FIG.29 and FIGS. 30-31A-C.

FIG. 29 is a graphical representation 1600 of frequency change 1602 overtime of waveforms of several generators during a burn-in test. Frequencychange (kHz) after X seconds of burn-in is shown along the vertical axisand ultrasonic surgical instrument device number is shown along thehorizontal axis. FIG. 29 shows frequency change data after prolongedburn-ins of an ultrasonic surgical instrument where the ultrasonicsurgical instrument is activated against the tissue pad for a prolongedperiod of time (a prolonged burn-in). The selection of 55,100 Hz limitsthis condition to no more than a 4 second time span or a frequency dropof about a 700 Hz from a nominal room temperature resonant frequency of55,800 Hz. Frequency change data 16021, 16022, 16023, 16024 was pulledfrom the generator 30, 500, 1002 data at corresponding 1, 2, 3, and 4seconds into the burn-in. The nominal start frequency for the fiveultrasonic surgical instruments was 55.8 kHz (blades started at roomtemperature). The second and fifth devices did not run long enough togenerate a full set of data for all times.

FIG. 30 is a graphical representation 1604 of normalized combinedimpedance, current, and frequency versus time waveforms of and powerconsumption, energy supplied, and temperature for one form of agenerator coupled to a corresponding ultrasonic instrument used to make10 successive cuts on tissue (e.g., on excised porcine jejunum tissue)as quickly as possible while keeping the generator running throughout.This data and the methods used to obtain it represent abusive useconditions.

The representative data in FIG. 30 is shown more clearly with referenceto FIGS. 31A-C. FIG. 31A is a graphical representation 1606 of impedanceversus time waveform 1608 and current versus time waveform 1610 of oneform of a generator during successive tissue cuts over a period of time.Impedance (Ohm) and Current (mA) are shown along the vertical axis andtime (Sec) along the horizontal axis.

FIG. 31B is a graphical representation 1612 of resonant frequencywaveform 1614 versus time of a signal of one form of a generator duringsuccessive tissue cuts over a period of time. Resonant frequency (kHz)is shown along the vertical axis and time (Sec) along the horizontalaxis.

FIG. 31C is a graphical representation 1616 of a power waveform 1618,energy waveform 1620, and temperature waveform 1622 versus time of oneform of a generator during successive tissue cuts over a period of time.Power (W), Energy (J), and Temp (C) are shown along the horizontal axisand time (Sec) along the horizontal axis.

Accordingly, with reference now to FIGS. 31A-C, as shown in thegraphical representation 1612, it can be seen that after the resonantfrequency curve 1614 has dropped 700 Hz (from 55.8 kHz to 55.1 kHz) at1615 on the third cut (which is a particularly abusive cut wherein thetissue was tip loaded. After the resonance frequency waveform 1614 hasdropped 700 Hz (from 55.8 kHz to 55.1 kHz) on the third cut, theultrasonic instrument begins to saturate the generator and the currentwaveform 1610 dips slightly in all successive cuts. Since the drivecurrent waveform 1610 is proportional to blade tip displacement, adipping current waveform 1610 results in slower speed of tissue effectand therefore a lower energy deposition rate (and lower rate of heating,i.e., frequency slope is less negative). Management of this change dueto dipping current waveform 1610 within an application sequence ispossible using both frequency change and frequency slope change as willbe described in connection with Examples 3 and 4 in subsequent sectionsof this specification.

FIG. 32 is a combined graphical representation 1630 of a frequencywaveform 1632, weighted frequency slope waveform 1634 (calculated viaexponentially weighted moving average with an alpha value of 0.1), andtemperature waveform 1636 versus time generated by a generator similarto one form of the generators described herein. The ultrasonic systemhad a room temperature resonant frequency (longitudinal mode) slightlyhigher than that for which TABLE 5 was constructed. Therefore, thefrequency threshold 1633 was increased accordingly from the 55,100 Hzshown in TABLE 5 to about 55,200 Hz shown in FIG. 33 as indicated by thedashed line. The activation was performed on tissue (e.g., on excisedporcine jejunum tissue) with an ultrasonic system having a roomtemperature resonance of about 55.9 kHz set on power level 5. Tissueseparation occurs at 6.25 seconds; one side of the tissue separates fromthe blade at about 8 seconds; and full separation occurs at about 10seconds. FIG. 33 is a graphical representation of a frequency versustime waveform 1632 of one form of a generator 30, 500, 1002. Frequency(kHz) is shown along the vertical axis and Time (Sec) is shown along thehorizontal axis. FIG. 33 shows the example of using a frequencythreshold 1633 only using parameters consistent with those shown inTABLE 5, but adjusted to about 55,200 Hz as indicated by the dashed line1633. The resonant frequency 1632 crosses the frequency threshold 1633(dashed horizontal line—set at 700 Hz below room temperature resonance)at about 11 seconds and a Response Set may be triggered at this time.

FIG. 34 is a graphical representation 1634 of weighted frequency slopeversus time waveform 1634 of one form of a generator. Weighted frequencyslope (kHz/Sec) is shown along the vertical axis and Time (Sec) is shownalong the horizontal axis. The frequency slope waveform 1634 iscalculated via exponentially weighted moving average with an alpha valueof 0.1. In FIG. 34, the frequency slope waveform 1634 crosses thefrequency slope threshold 1635 (dashed horizontal line) and a ResponseSet may be triggered at about 5.8 seconds.

The remaining Examples 3 and 4 relate to the use of multiple ConditionSets, which require a more complex application of the tissue algorithmand includes the monitoring of frequency slope and/or frequency againsttheir respective thresholds and may include a hierarchical approach totriggering response sets.

Example 3: Triggering a Response Set Based on Both the Frequency SlopeThreshold and the Frequency Threshold

A third example case includes triggering a Response Set based on boththe frequency slope threshold and the frequency threshold. TABLE 6contains representative parameters for this objective in connection withsurgical instruments such as any one of the surgical instruments 19,190, 1000 disclosed herein comprising corresponding ultrasonicinstruments such as the ultrasonic instruments 100, 120, 1004 disclosedherein.

TABLE 6 Representative Parameters for Triggering Audio Indications byFrequency Slope and Frequency Thresholds (two Condition Sets utilized)Parameter Value* Condition Set 1 Pulsing flag 0 Condition Set 1 LCDdisplay flag 0 Condition Set 1 Audio flag 1 Condition Set 2 Pulsing flag0 Condition Set 2 LCD display flag 0 Condition Set 2 Audio flag 1Required time before triggered, Condition 50 msec Set 1 Minimum latchtime, Condition Set 1 0 msec* Frequency Slope Thresholds (one for eachlevel 5: −0.060 kHz/sec power level), Condition Set 1 level 4: −0.053kHz/sec level 3: −0.045 kHz/sec level 2: −0.038 kHz/sec level 1: −0.030kHz/sec Frequency Threshold, Condition Set 1 56,000 Hz* Required timebefore triggered, Condition 50 msec Set 2 Minimum latch time, ConditionSet 2 0 msec* Frequency Slope Thresholds (one for each level 5: 1.00kHz/sec* power level), Condition Set 2 level 4: 1.00 kHz/sec* level 3:1.00 kHz/sec* level 2: 1.00 kHz/sec* level 1: 1.00 kHz/sec* FrequencyThreshold, Condition Set 2 55,100 Hz Time to wait 100 msec Cross-backFrequency Slope Threshold −0.020 kHz/sec First Pulse Amplitudes (one foreach N/A power level) First Pulse Time N/A Second Pulse Amplitudes (onefor each N/A power level) Second Pulse Time N/A *These parameter valuesare set to an appropriate extreme such that they do not effectively takepart in logic flow (e.g. set to always be “true”)

In this case of Example 3, a tiered or hierarchical response isdemonstrated. The combined logic of the frequency slope threshold andthe frequency threshold will be illustrated using the same graphicalrepresentations shown in FIGS. 32-34. In FIG. 34, Condition Set 1 istriggered by the frequency slope waveform 1634 crossing the frequencyslope threshold 1635 value at about 6 seconds. The Response Set forCondition Set 1 may include a low level audible indicator, for example.As the user continues to activate the instrument with minimalintervening tissue, Condition Set 2 is triggered as the resonantfrequency drops below the frequency threshold 1633 at about 11 secondsas shown in FIG. 33. The Response Set for Condition Set 2 may be anelevated audible indicator, for example.

Example 4: Triggering a Response Set Based on Both the Frequency SlopeThreshold and the Frequency Threshold

A fourth example extends to the application of both frequency andfrequency slope thresholds during abusive conditions of the surgicalinstrument. For various reasons, the frequency slope signal levels maydiminish (i.e., become less negative) with extended application.

In abusive conditions, frequency, frequency slope, and current waveformsmay deviate from normal operation may be generated while the ultrasonicinstrument is constantly activated at a power level 5, where the jaws ofthe ultrasonic instrument were opened for 1 second, then closed for 1second and repeated for 17 cycles.

When an ultrasonic instrument is activated multiple times directlyagainst the pad, the characteristic frequency slope waveform in a firstregion before the generator saturates becomes less negative than in asecond after the generator saturates due, in large part, to the systemefficiency and resulting displacement/current drop. In thenon-saturation region of the frequency slope waveform, the ultrasonicsystem has not yet saturated and current is maintained at or near thetarget current for power level 5. In the saturation region of thefrequency slope waveform, the current (and therefore blade tipdisplacement) continually drops causing the frequency slope to increase(rate of heating drops). Note that at after several abusive cycles,e.g., the fourth abuse cycle, which is the approximate demarcationbetween the non-saturation and saturation regions, the resonantfrequency drops consistent with FIGS. 29-31A-C. Separate Conditions Setsfor each of the non-saturation and saturation regions may be applied. Afirst frequency slope threshold may be employed in the non-saturationregion when resonant frequency conditions are above a predeterminedfrequency threshold and a second, less negative frequency slopethreshold may be employed in the saturation region when resonantfrequency conditions are below the same predetermined frequencythreshold.

A weighted frequency slope (kHz/sec) versus time waveform may be of oneform of a generator. When the instrument is used abusive conditionsagainst the pad, the characteristic frequency slope waveform in thenon-saturation region becomes less negative than in the saturationregion due to material softening and a corresponding reduction in padcoefficient of friction. In the non-saturation region of the frequencyslope waveform corresponds to when the tissue pad has not yet begun toheat significantly. In the saturation region of the frequency slopewaveform, the pad begins to soften and the interface between the bladeand the pad becomes more lubricious causing the frequency slope waveformto increase (rate of heating drops). Separate Conditions Sets for eachof the non-saturation and saturation regions may be warranted. A firstfrequency slope threshold may be employed in the non-saturation regionwhen resonant frequency conditions are above a predetermined frequencyslope threshold and a second, less negative frequency slope thresholdmay be employed in the saturation region when the resonant frequency isbelow the same predetermined frequency slope threshold.

Another example case is now considered. TABLE 7 contains parameters foran ultrasonic instrument where two Condition Sets are used to accountfor diminishing frequency slope signal levels due to system saturationand dropping current.

TABLE 7 Representative Parameters for Triggering Audio Indications byFrequency Slope and Frequency Thresholds, accounting for diminishingfrequency slope due to system saturation (two Condition Sets utilized)Parameter Value* Condition Set 1 Pulsing flag 0 Condition Set 1 LCDdisplay flag 0 Condition Set 1 Audio flag 1 Condition Set 2 Pulsing flag0 Condition Set 2 LCD display flag 0 Condition Set 2 Audio flag 1Required time before triggered, Condition 50 msec Set 1 Minimum latchtime, Condition Set 1 0 msec* Frequency Slope Thresholds (one for eachlevel 5: −0.060 kHz/sec power level), Condition Set 1 level 4: −0.053kHz/sec level 3: −0.045 kHz/sec level 2: −0.038 kHz/sec level 1: −0.030kHz/sec Frequency Threshold, Condition Set 1 56,000 Hz* Required timebefore triggered, Condition 50 msec Set 2 Minimum latch time, ConditionSet 2 0 msec* Frequency Slope Thresholds (one for each level 5: −0.045kHz/sec power level), Condition Set 2 level 4: −0.038 kHz/sec level 3:−0.030 kHz/sec level 2: −0.024 kHz/sec level 1: −0.020 kHz/sec FrequencyThreshold, Condition Set 2 55,100 Hz Time to wait 100 msec Cross-backFrequency Slope Threshold −0.020 kHz/sec First Pulse Amplitudes (one foreach power N/A level) First Pulse Time N/A Second Pulse Amplitudes (onefor each N/A power level) Second Pulse Time N/A *These parameter valuesare set to an appropriate extreme such that they do not effectively takepart in logic flow (e.g., set to always be “true”)

The data generated for this example run were generated using anultrasonic instrument to make ten successive cuts in jejunum tissue asquickly as possible. Using the parameter values from TABLE 7, theFrequency vs. Time plots for the example sample case are shown in FIGS.35-36.

FIG. 35 is a graphical representation 1800 of a frequency versus timewaveform 1802 of one form of a generator over ten cuts on tissue (e.g.,jejunum tissue) and a graphical representation 1804 of a temperatureversus time waveform 1805. For the graphical representation 1800,Frequency (Hz) is shown along the vertical axis and Time (Sec) is shownalong the horizontal axis. For the graphical representation 1804,Temperature (° F.) is shown along the vertical axis and Time (Sec) isshown along the horizontal axis.

FIG. 36 is a graphical representation 1805 of the frequency versus timewaveform 1802 shown in FIG. 35 of one form of a generator over ten cutson tissue (e.g., jejunum tissue) with activation of intervening tissueat portions indicated by reference number 1806. Frequency (Hz) is shownalong the vertical axis and Time (Sec) is shown along the horizontalaxis.

The frequency waveform 1802 shown in FIGS. 35 and 36 is for the examplecase using two Condition Sets to account for diminishing frequency slopedue to electrical system saturation (diminishing displacement). Notethat this is the same test run as is shown in FIGS. 29-31A-C. In FIG.36, the highlighted portions 1806 indicates activation with interveningtissue (frequency drops, shape of local frequency curve related todryness of tissue—shallow start slope, steepens as tissue dries), thehighlighted portions 1808 indicate activation with minimal or nointervening tissue (local frequency slope very steep, curve shape ismore linear, steepens gradually), the section of the curve with nohighlighted portions 1810 indicates time within which the device isbeing repositioned for the next cut, blade cools in air and coolsrapidly when placed on tissue (frequency rises).

FIG. 37 is a graphical representation 1812 of a frequency slope versustime waveform 1814 of one form of a generator over ten cuts on jejunumtissue. Frequency slope (kHZ/Sec) is shown along the vertical axis andTime (Sec) is shown along the horizontal axis. Region B of the frequencyslope waveform 1814 shows the area of the ten cut run where ConditionSet 2 is triggered prior to Condition Set 1 for the first time duringthe ten cut run (frequency is below 55.1 kHz and frequency slope is lessthan −0.045 kHz/sec). The condition illustrated in Region B, whereCondition Set 2 is triggered prior to Condition Set 1, is desiredbecause the ultrasonic system is consistently saturating by this pointin the run (voltage is saturating and current is diminished resulting indiminished displacement and, therefore, diminished rate of heatingrequiring a greater frequency slope threshold).

FIG. 38 is a graphical representation 1816 of a power versus timewaveform 1818 representative of power consumed by a one form of agenerator over ten cuts on tissue (e.g. jejunum tissue). Power (W) isshown along the vertical axis and Time (Sec) is shown along thehorizontal axis.

FIG. 39 is a graphical representation 1820 of a current versus timewaveform 1822 of one form of a generator over ten cuts on jejunumtissue. Current (mA) is shown along the vertical axis and Time (Sec) isshown along the horizontal axis.

Having described the basic application of the tissue algorithm discussedin connection with the logic flow diagrams 1200, 1300, 1400 shown inFIGS. 20-22 in terms of monitoring the frequency slope, resonantfrequency, or both against their respective thresholds, the discussionnow turns to a description of the latching logic and corresponding useas it relates to the tissue algorithm. The motivations for adding thelatching logic to the tissue algorithm are: (a) to prevent a ConditionSet from resetting (Condition Set changes from true to false) due to ablade/pad interface becoming more lubricious during a blade on pad abusecondition; and (b) to prevent a Condition Set from resetting (ConditionSet changes from true to false) due to pulsed activation where periodsof rapid heating are interweaved with periods of less rapid heating(sections of heat flux into the blade and sections of heat flux out ofthe blade are interweaved). The first and second of these motivationsare shown in FIGS. 48 and 49 illustrate, respectively. As definedearlier in this disclosure, the two latch parameters addressing thesemotivations are “cross-back frequency slope threshold” as shown in FIG.40 and “minimum latch time.” For completeness of disclosure, FIG. 43shows calculated frequency slope curves for the pulsed run shown inFIGS. 41 and 42A-C.

FIG. 40 is a graphical representation 1900 of a “cross-back frequencyslope threshold” parameter in connection with frequency slope versustime waveform 1902. As shown in FIG. 40, the “frequency slope threshold”1904 is shown by the horizontal dashed line at −0.15 kHz/sec. The“cross-back frequency slope threshold” 1906 is shown by the horizontaldash-dot line at −0.02 kHz/sec. In this instance, the Condition Set ismet and a Response Set is triggered when the local calculated frequencyslope crosses the “frequency slope threshold” as shown by arrow 1908pointing down. The Condition Set is not met (Response Set is no longertriggered) when the local calculated frequency slope crosses over the“cross-back frequency slope threshold” as shown by arrow 1910 pointingup. Note that without using the “cross-back over frequency slopethreshold” in this case, the Response Set would not have been triggeredwhen the local frequency slope crossed back over the horizontal dashedline 1904 at about 4.7 seconds shown at cross over point 1911.

FIG. 41 is a combined graphical representation 1920 of a pulsedapplication of one form of an ultrasonic instrument on an excisedcarotid artery showing normalized power, current, energy, and frequencydata plotted versus time.

FIG. 42A is a graphical representation 1921 of an impedance versus timewaveform 1922 and a current versus time waveform 1924 of one form of agenerator during successive tissue cuts over a period of time. Theimpedance (Ohms) and current (mA) is shown along the vertical axis andTime (Sec) is shown along the horizontal axis.

FIG. 42B is a graphical representation 1923 of a frequency versus timewaveform 1925 of one form of a generator during successive tissue cutsover a period of time. Frequency (kHz) is shown along the vertical axisand Time (Sec) is shown along the horizontal axis.

FIG. 42C is a graphical representation 1930 of power waveform 1926,energy waveform 1927, a first temperature waveform 1928 and a secondtemperature waveform 1929 plotted versus time as of one form of agenerator during successive tissue cuts over a period of time. Power(W), Energy (J), and Temperature (° C.) are shown along the verticalaxis and Time (Sec) is shown along the horizontal axis.

FIGS. 42A-C show a pulsed application of an ultrasonic instrument on anexcised carotid artery where the First Pulse Time is 1 second, the FirstPulse Amplitude is 100% of power level 3 output current. The SecondPulse Time is 1.5 seconds and the Second Pulse Amplitude is less than10% of power level 3 output current. Of note, the resonant frequencywaveform 1925 exhibits sections of both heating (heat flux into theblade) and cooling (heat flux out of the blade). The “minimum latchtime” parameter, defined herein as the minimum amount of time forresponse(s) to a Condition Set X to be triggered, is intended tomaintain triggering of a Response Set during pulsed application (oneexample of a latch time may be about 1 second). Of additional note, asshown in FIG. 42A, the load or impedance waveform 1922 does not dropbelow 200 Ohms throughout the run sequence. This may be favorableconsidering that the impedance waveform 1922 for a marching applicationconsistently drops below about 150 Ohms while operating in air betweencuts implying that an impedance limit may be used for resettingCondition Sets. In one aspect this impedance limit may be used forimplementation of the “low drive in air” concept as disclosed in U.S.Pat. No. 5,026,387 to Thomas.

FIG. 43 is a graphical representation 1932 of a calculated frequencyslope waveform 1934 for the pulsed application shown in FIG. 41 andFIGS. 42A-C plotted on a gross scale. FIG. 44 is a zoomed in view of thegraphical representation of the calculated frequency slope waveform 1934for the pulsed application shown in FIG. 43. Both FIGS. 43 and 44 showthe calculated frequency slope waveform 1934 for the pulsed applicationshown in FIG. 41 and FIGS. 42A-C. Frequency slope (kHz/Sec) is shownalong the vertical axis and Time (Sec) is shown along the horizontalaxis. Two scales are shown, where FIG. 43 shows a gross scale forfrequency slope and FIG. 44 shows a “zoomed in” view. For frequencyslope, the same trends seen under continuous drive are shown in pulseddrive including values that correlate well to heat flux into (negativefrequency slope) and out of the blade (positive frequency slope). Thetransient nature of the frequency curve and frequency slope curve due topulsing, combined with the moving average calculation of frequency slopemake use of the frequency slope curve during pulsing difficult. Of note,the tissue separated at 13 seconds. As can be seen in FIG. 43 andespecially FIG. 44, the rate of cooling can be used to trigger aresponse correlating rapid cooling in the dwell portions of pulsedoutputs to the completion of a tissue transection using logic (not shownby logic flows in FIGS. 20-22) where frequency slope waveform 1934exceeds a threshold value, in this case of about 0.04 kHz/sec whensampled at the ends (i.e., the settled regions) of the dwell periods. Ascan be seen in FIG. 42A, the impedance waveform 1922 can be used totrigger a response correlating high impedance (high resistance tomechanical motion or vibration) to the completion of a tissuetransection using logic (again, not shown by logic flows in FIGS. 20-22)where transducer impedance waveform 1922 exceeds a threshold value, inthis case of about 700 Ohms when sampled at the beginnings (i.e., thesettled regions) of the dwell periods.

FIG. 45 is a graphical representation 1936 of other data waveforms 1938of interest such as impedance, power, energy, temperature. In FIG. 45,the vertical scale to the right applies to the impedance curve only.

The present disclosure now turns to considerations for power level andclamp pressure profile in an ultrasonic instrument. The rate of heatingof a blade to pad interface is proportional to blade displacement,interface coefficient of friction and load (clamp pressure or normalforce). Testing was performed to assess the tissue algorithm at a rangeof displacements (power levels) and device specific combinations ofclamp pressure and coefficient of friction (defined largely by padmaterials and blade coatings).

FIG. 46 is a graphical representation 1940 of a summary of weightedfrequency slope versus power level for various ultrasonic instrumenttypes. Weighted frequency slope (kHz/Sec) is shown along the verticalaxis and power level, device type, and device are shown along thehorizontal axis. The instruments used to generate the data summarized inthe graphical representation 1940 are generally commercially availablewith some exceptions. One test procedure included clamping the device,activating the device for three seconds, and calculating the averagefrequency slope over the full three seconds. Other metrics, however, maybe employed. For most devices, the data summarized in FIG. 46 would beapproximately indicative of the minimum frequency slope value. FIG. 46shows the frequency slope summary data for burn-in testing on shearstype ultrasonic instruments where the instruments were clamped, thenactivated for 3 seconds, then unclamped—the average frequency slope overthe full three seconds of activation was calculated and plotted asshown.

Based on predetermined tests and test data from FIG. 46, the followingfrequency slope thresholds are suggested for the main power levels ofuse with some ultrasonic instruments:

-   -   (1) level 5 frequency slope threshold: −0.060 kHz/sec;    -   (2) level 3 frequency slope threshold: −0.045 kHz/sec;    -   (3) level 5 frequency slope threshold: −0.070 kHz/sec; and    -   (4) level 3 frequency slope threshold: −0.050 kHz/sec.

System stiffness includes both blade stiffness (cantilevered beam) andpad stiffness/pad thermal stability. The more differentiated theunloaded (no tissue) system stiffness is from the loaded (clamped ontissue) system stiffness, the more robust the tissue algorithmperformance. Other constraints, of course, may limit system stiffness onthe high end.

Further exploration of displacement effects were analyzed based on alarger set of data. For the ultrasonic system, power levels areessentially differentiated by output current target values and, current,which is proportional to vibratory amplitude or displacement. Analysisof this data also may include digital smoothing of the frequency data toobtain usable frequency slope curves.

FIGS. 47-49 show frequency and current versus time waveforms obtainedusing one form of a generator and an ultrasonic instrument to excise aporcine carotid artery at power level 5.

FIG. 47 is a graphical representation 1970 of resonant frequency versustime waveform 1972, an averaged resonant frequency versus time waveform1974, and a frequency slope versus time waveform 1976 of one form of agenerator. Frequency (kHz) and Frequency Slope (kHz/Sec) are shown alongthe vertical axes and Time (Sec) is shown along the horizontal axis. Thefrequency slope waveform 1976 is based on the averaged frequency dataand was obtained by post processing the frequency waveform 1972 data.The raw frequency data is plotted as well as smoothed (via simple movingaverage) frequency data and frequency slope (calculated from thesmoothed data because the raw frequency data contains stair-stepping dueto rounding of the streamed data). The average resonant frequencywaveform 1974 is obtained via a 70 msec moving average (kHz) of theresonant frequency data.

FIG. 48 is a zoomed in view 1978 of the resonant frequency versus timewaveform 1972 and the averaged resonant frequency versus time waveform1974 of one form of a generator. Frequency (kHz) is shown along thevertical axis and Time (Sec) is shown along the horizontal axis.

FIG. 49 is a zoomed in view 1980 of the resonant frequency waveform 1972and a current versus time waveform 1982 of one form of a generator.Frequency in (Hz) and Current (A) is shown along the vertical axes.

In FIGS. 48 and 49, the respective zoomed in views 1978, 1980 are shownto see the effect of smoothing frequency data and to see riseinformation at the start of the application, which may be helpful forassessment of parameters such as Time to Wait.

Other aspects of the tissue algorithm described herein may be applied tosituations when little to no intervening tissue remains (between theultrasonic blade and the clamp arm) and waste energy is being dumpedinto the end effector. Accordingly, in one form, the tissue algorithmmay be modified to provide feedback to the user relative to thissituation. Specifically, the tissue algorithm leverages the fact thatthe resonance of an ultrasonic blade changes relative to temperature(decreases with increasing temperature and increases with decreasingtemperature).

In one aspect the tissue algorithm disclosed herein may be employed tomonitor the frequency slope of a waveform where the algorithm monitorsthe change in resonant frequency slope to indicate the changingcondition of the tissue. In the case shown in FIG. 50, for example, theinflection of the frequency response curve correlates to the point atwhich the tissue begins to separate (i.e., there is a tissue tag and theuser continues to activate the instrument), which can be verified byexperimentation. The change in frequency slope can be used to providevisual, audible and/or tactile feedback (e.g., distinct beeping sound,flashing light, tactile vibration, among others previously discussed) tothe user (that waste energy is being dumped into the end effector) orthe generator output could be controlled or stopped.

In another aspect, the tissue algorithm disclosed herein may be employedto monitor the frequency threshold of a waveform, where the algorithmmonitors the change in frequency as the waveform crosses some thresholdor difference from some known state (e.g., room temperature). Similar tomonitoring the frequency slope, as the change in frequency drops belowsome threshold value or difference, an indication can be given to theuser that the device end effector is heating at an accelerated rate.Again, FIG. 50 provides a graphical illustrative view of a frequencythreshold.

In yet another aspect, the tissue algorithm disclosed herein may beemployed to monitor the frequency slope change and the frequencythreshold in combination. The combination of a significant change infrequency slope and a drop in frequency below some threshold can be usedto provide an indication of high temperature.

Turning now to FIG. 50, is a graphical representation 1990 of normalizedcombined power 1991, impedance 1992, current 1993, energy 1994,frequency 1995, and temperature 1996 waveforms of one form of agenerator coupled to an ultrasonic instrument. As shown, the tissuebegins to separate at 6.672 seconds. From this point until the tissuefully separates, about 55-60% of the total frequency drop is obtained,the temperature increases by a factor of about 1.92 (from 219° C. to418° C.) and about 28% of the total energy applied is delivered. Thelocal slopes of the frequency vs. time waveforms are shown by a firstset of dashed lines 1997, which represents a rapid change in theresonant frequency slope. Monitoring this slope 1997 affords theopportunity to indicate a dramatic change which typically occurs whenthere is limited to no intervening tissue and the vast majority of poweris being applied to the blade/tissue pad interface. Likewise, thefrequency change from its resonance in a known state (e.g., roomtemperature) can be used to indicate high temperatures—a frequencychange threshold is shown with a second dashed line 1998. Also, acombination of these two, frequency slope change and frequency changethreshold, can be monitored for purposes of indication. Note that thefrequency changes in this case from an initial value of 55,712 Hz to anend value of 55,168 Hz with the threshold shown at about 55,400 Hz.

In some example forms, surgical and/or instrument-related conditions mayreduce the ability of the Condition Sets described above to accuratelyreflect the state of the instrument. In some situations, the blade mayheat more slowly than normal, causing the resonant frequency to behigher and the frequency slope to be more gradual that expected. Oneexample of such a situation may occur when tissue is adhered to anon-clamping surface of the blade. In this and other situations, a moregradual rate of heating is seen, even upon completion of a tissue bitewhen minimal or no tissue is present between the blade and clamp armpad. This may, in turn, delay the meeting of various Condition Setsbased on comparing local frequency slope to a frequency slope thresholdparameter and/or comparing local resonant frequency to a frequencythreshold parameter. As a result, Response Sets implementing audibletones, pulsed modes, current deactivation, etc., may be unnecessarilydelayed.

FIGS. 51A and 51B are graphical representations of resonant frequencyand frequency slope, respectively, displayed by one form of anultrasonic instrument during an ultrasonic tissue bite. The biteillustrated in FIGS. 51A and 51B resulted in gradual heating of theblade of an ultrasonic instrument. FIG. 51A is a chart showing time on ahorizontal axis 2100 and blade resonant frequency on a vertical axis2104. A plot 2105 illustrates the resonant frequency of the blade overtime. FIG. 51B is a chart showing time on a horizontal axis 2104 andfrequency slope on a vertical axis 2106. Plot 2107 illustrates frequencyslope over time. In the example cut shown in FIGS. 51A and 51B, tissueseparation occurred at between 2 and 3 seconds. The tissue separationcaused a small change in resonant frequency, indicated at 2108, and ashallow minimum in frequency slope, indicated at 2100. The signalfeatures 2108, 2110, however, may not be sufficient to timely trigger aCondition Set requiring frequency slope to drop below a frequency slopethreshold parameter and/or requiring resonant frequency to drop below afrequency threshold parameter.

FIGS. 52A and 52B are graphical representations of resonant frequencyand frequency slope, respectively, displayed by one form of anultrasonic instrument during another ultrasonic tissue bite. Again, theillustrated tissue bite resulted in gradual heating of the blade of anultrasonic instrument. Plot 2112 illustrates resonant frequency versustime for the tissue bite of FIGS. 52A-52B while plot 2114 illustratesfrequency slope versus time for the tissue bite of FIGS. 52A-52B. In theillustrated tissue bite, tissue began to separate from the blade atbetween five and seven seconds, and a tissue tag fully separated fromthe blade at about nine seconds. As can be seen, the tissue separationcaused a small change in resonant frequency, beginning at 2116, and asmall minimum in the frequency slope, as indicated by 2118. Again,however, due to slow heating of the blade, the signal features 2116,2118 may not be sufficient to trigger a desired Condition Set.

In certain forms, generators, such as 30, 500, 1002, and/or ultrasonicsurgical instruments, such as 100, 120, 1004, may be implemented withone or more Condition Sets that consider a dynamic frequency cut-off.These, and other condition sets described herein, may be actuated by theclinician upon receipt of an input signal from a switch, button or pedalor, in some forms, run on background while other algorithms are executed(e.g., instrument control algorithms). For example, a baseline resonantfrequency may be captured when ultrasonic impedance exceeds a thresholdimpedance. For example, exceeding the threshold impedance may indicatethat the clamp arm is closed (e.g., a tissue bite is about to begin).One or more Condition Sets may comprise a baseline frequency cut-offcondition that is met when the resonant frequency of the blade differsfrom the baseline frequency by more than a baseline deviation thresholdparameter. In certain forms, the baseline frequency cut-off condition ismet even when other conditions based on resonant frequency or frequencyslope are not met. When utilized in a logical “Or” arrangement withother conditions, baseline frequency cut-off conditions may allowcertain Condition/Response Set pairs to be triggered in situations, suchas those described above, where blade heating is more gradual thannormal.

FIG. 53 is a logic flow diagram of one form of a tissue algorithm 2120implementing a baseline frequency cut-off condition that may beimplemented in one form of a generator to consider a baseline resonantfrequency of an ultrasonic blade. At 2122, activation of the bladebegins. For example, the generator may be activated at a particularpower level, indicated as “N.” Optionally, at 2124, the generator maywait a threshold time period. The threshold time period may besufficient to allow any frequency or other transients occurring uponactivation to dissipate. For example, FIGS. 54A and 54B are graphicalrepresentations of blade frequency demonstrated in different exampleultrasonic activations. Plot 2136 shows frequency versus time for afirst example activation, and demonstrates a transient frequency featureor blip at 2140. Plot 2138 shows frequency versus time for a secondexample activation, and demonstrates a transient feature or blip 2142.

Referring back to 2124, the algorithm 2120 may utilize any suitablethreshold time period that extends beyond the dissipation of all or mostsignal transients or blips. For example, in some forms, the thresholdtime period may be between 0.1 and 1.0 seconds. In some example forms,the threshold time period may be between 0.2 and 0.5 seconds. In oneexample form, the threshold time period may be about 0.2 seconds. At,2126 the generator may receive an indication of the ultrasonicimpedance. In various example forms, the ultrasonic impedance representsan electrical impedance of the transducer blade system, and/or animpedance of the “motional branch,” as described herein above. At 2128,the generator may determine whether the ultrasonic impedance is greaterthan a threshold impedance. For example, this may the closing of theclamp arm either against the blade or against tissue. In some forms, thegenerator at 2128 may not conclude that the ultrasonic impedance isgreater than the threshold unless it is greater than the threshold for aset amount of time (a “time above impedance” period). The time aboveimpedance period may be any suitable value and may be between 10 and 100msec including, for example, 30 msec.

If the ultrasonic impedance is not above the threshold impedance at 2128(or is not above the threshold impedance for the “time above impedance”period), the generator may return to 2126 and 2128, continuing tomonitor the ultrasonic impedance until it does exceed the thresholdimpedance. If the ultrasonic impedance is above the threshold impedanceat 2128, the generator may capture a local resonant frequency of theblade as a baseline frequency at 2130. As the activation continues, thegenerator may, at 2132, determine whether a frequency delta, ordifference between the baseline frequency and the local resonantfrequency of the blade exceeds a baseline deviation threshold parameter.If the frequency delta exceeds the baseline deviation thresholdparameter, then the baseline cut-off condition may be met. If themeeting of the baseline cut-off condition causes a complete ConditionSet to be met, than a corresponding Response Set may be triggered at2134. In some forms, the baseline cut-off condition is not met until orunless the frequency delta is above the baseline deviation thresholdparameter value for a time above frequency delta period.

In some example forms, utilizing a baseline frequency and frequencydelta, as described with respect to the algorithm 2120, also addressesissues arising in surgical situations where the resonant frequency ofthe ultrasonic blade floats between activations or cuts. This may occur,for example, when an ultrasonic blade is used for multiple cuts withoutbeing deactivated. FIG. 55 is a graphical representation of resonantfrequency 2144 and ultrasonic impedance 2150 over time for one formincluding multiple cuts with an ultrasonic blade. Each feature 2147represents a distinct tissue bite, cut or other tissue treatmentutilizing the ultrasonic blade. It can be seen from FIG. 55 that, at theoutset of each cut, the resonant frequency spikes (e.g., as the clamparm closes on tissue). For example as the clamp arm closes on tissue,the blade may be brought into contact with relatively cool tissue. Thismay cool the blade, causing the temporary positive slope of the resonantfrequency, as shown. As ultrasonic energy is applied to the blade, itbegins to heat, causing the illustrated decline in resonant frequencyfor each cut. Referring now to FIG. 55 in conjunction with the algorithm2120, the ultrasonic impedance may exceed the harmonic thresholdimpedance at the outset of each cut 2147, causing the generator tocapture a baseline frequency at that time. For example, line 2148indicates an example point in time where the ultrasonic impedanceexceeded the threshold impedance and a baseline frequency was taken.

In certain forms, a baseline frequency cut-off condition may be utilizedin a common Condition Set with one or more other conditions. FIG. 56 isa logic flow diagram of a tissue algorithm 2150 that may be implementedin one form of a generator and/or instrument to implement a baselinefrequency cut-off condition in conjunction with other conditions. At2152, the generator may calculate a frequency delta. The frequency deltamay be calculated as described above, for example, with respect to thealgorithm 2120. For example, the generator may capture a baselinefrequency upon ultrasonic impedance exceeding the impedance threshold,and find the frequency delta as a difference between the local resonantfrequency and the baseline frequency. At 2154, the generator may applyone or more other conditions. Such conditions may be similar to thosedescribed above with respect to FIGS. 20-22. For example, the otherconditions may include whether the local frequency slope is less than afrequency slope threshold parameter 1404, whether the local resonantfrequency is less than a frequency threshold parameter, etc. The otherconditions may be applied in any logical manner. For example, the otherconditions may be considered met of one of the other conditions is met(e.g., a logical OR), may be considered met only if all of the otherconditions are met (e.g., a logical AND), etc.

If the other conditions are met at 2154, the Condition Set may beconsidered met, and the generator may trigger the appropriate ResponseSet at 2158. If the other conditions are not met at 2154, the generatormay determine if the frequency delta is greater than the baselinedeviation threshold parameter at 2156. If not, then the other conditionsmay be applied again at 2154. If yes, then the Condition Set may beconsidered met even though the other conditions are not met. Once aResponse Set is triggered at 2128, the Response Set may continue to beexecuted until parameters for exiting the Response Set are determined tobe met at 2160 and the triggered condition is exited at 2162. Suchparameters may include, for example, the expiration of a Condition Setminimum latch time parameter, frequency slope exceeding a cross-backfrequency slope threshold, etc.

In various example forms, a baseline frequency cut-off condition may beutilized in the context of the logic flow diagrams 1200, 1300, 1400 ofFIGS. 20-22 described above. For example, FIG. 57 is a logic flowdiagram of one form of a signal evaluation tissue algorithm portion1300′ of the tissue algorithm 1200 shown in FIG. 20 considering abaseline frequency cut-off condition. The algorithm 1300′ may beexecuted in a manner similar to that of the algorithm 1300 describedherein above. At 2164, however, the generator may determine whether aload monitoring flag is set for a given Condition Set X. In some exampleforms, the load monitoring flag 2167 may indicate whether a frequencycut-off condition is to be considered.

If the load monitoring flag 2167 is not set, the frequency delta may beset to zero (e.g., a frequency delta of zero may never exceed thebaseline derivation threshold, allowing the algorithm 1300′ to operatein a manner similar to that of the algorithm 1300). If the loadmonitoring flag 2167 is set, the generator may execute a load monitoringalgorithm 2166, which may receive as input a maintain status flag 2168.The maintain status flag may indicate to the generator whether to wait athreshold time period before considering ultrasonic impedance so as toavoid transient features or blips as illustrated with respect to FIGS.54A, 54B.

The load monitoring algorithm 2166 may return the frequency delta.Additional details of how the load monitoring algorithm returns thefrequency delta are provided herein below with respect to FIG. 58.Referring again to FIG. 57, at 2172, the generator may calculate a slopebetween two or more resonant frequency data points and may utilizeappropriate averaging and/or smoothing, as described herein above. Inputat 2172 may include an incoming resonant frequency data point 2174(F_(t)) and an incoming ultrasonic impedance data point 2176(|Z|_(mot)), which may be instantaneous and/or averaged over severaldata points. The time to wait timer may be applied at 1306 as describedabove. If the time to wait has elapsed, the generator may execute one ormore condition set algorithms 1400/1400′, as described herein. Eachcondition set algorithm 1400/1400′ may receive as arguments theultrasonic impedance, the frequency slope, the resonant frequency, andthe frequency delta.

FIG. 58 is a logic flow diagram of one form of a load monitoringalgorithm 2166 that may be implemented in one form of a generator. Theload monitoring algorithm 2166 may take as input a local ultrasonicimpedance (|Z|_(mot)), a local resonant frequency (F_(t)) and the stateof the maintain status flag (F_(Maintain status)). At 2178, thegenerator may determine whether the maintain status flag is set. If not,then the frequency delta (F_(delta)) may be set to zero at 2210. Incertain forms, setting the frequency delta to zero may effectivelydisable load monitoring. If the maintain status flag is set, a maintaintimer 2180 may be incremented at 2180. At 2182, the generator maydetermine whether the maintain timer has reached the threshold timeperiod for blip dissipation has been met. If not, the frequency deltamay be set to zero at 2210. If yes, the generator may determine at 2184whether the received local ultrasonic impedance is greater than athreshold impedance 2186. If yes, a load timer for implementing the timeabove threshold impedance described above may be incremented at 2192.

At 2190, the generator may determine if the load timer is greater thanthe time above threshold impedance 2188. If yes, the generator maydetermine whether a baseline frequency latch is set at 2194. Thebaseline frequency latch may prevent the baseline frequency frombouncing during a jaw closure event, indicated by ultrasonic impedance.For example if the baseline frequency latch is set, it may indicate thata baseline frequency has already been taken for a given load event. Ifthe baseline frequency latch is not set, the generator may set the latchand set the baseline frequency as the current resonant frequency of thesystem at 2196. At 2206, the generator may again determine whether thebaseline frequency latch is set. If yes, the frequency delta may be setto the baseline frequency minus the local resonant frequency at 2208. Ifthe baseline latch is not set, then the frequency delta may be set tozero at 2210.

Referring back to 2184, if the ultrasonic impedance is not greater thanthe threshold impedance, the generator may reset the load timer at 2198.At 2202, the generator may determine whether the ultrasonic impedance isless than a reset threshold impedance (|Z|_(mot) Reset Threshold). Ifthe ultrasonic impedance is less than the reset threshold impedance, thegenerator may reset the baseline frequency latch at 2204 and proceed to2206, as described above. If the ultrasonic impedance is not less thanthe reset threshold impedance, the generator may proceed to 2206, asdescribed above, without resetting the baseline frequency latch.

FIG. 59 is a logic flow diagram 1400′ for evaluating Condition Sets forthe signal evaluation tissue algorithm 1300′ shown in FIG. 57 that maybe implemented in one form of a generator. At 2212, the generator mayimplement logic for determining if an unfiltered Condition Set is metfor the evaluated Condition Set. Logic 2212 is described in more detailbelow with respect to FIG. 60 and may return a “true” or “false”response. At 2214, the generator may determine whether a filteredCondition Set latch is set. The filtered Condition Set latch may be set,as described below, when the filtered Condition Set is met, for example,so as to ensure that the filtered Condition Set is indicated to be setfor a threshold period of time. If the filtered Condition Set latch isset, the generator may increment a latch timer at 2218 and determinewhether the unfiltered Condition Set is met at 2220. If the unfilteredcondition set is met, then the logic flow 1400′ may return an indicationthat the filtered Condition Set is met.

If the unfiltered condition set is not met at 2220, the generator mayevaluate whether the Condition Set is still met at 2222. For example,the generator may determine (i) whether the filtered Condition Set latchtimer has exceeded a minimum latch timer 1422; and (ii) whether thefrequency slope is greater than a cross-back frequency slope threshold1424; and (iii) [whether load monitoring 2167 is disabled OR whether aload event has completed] (e.g., whether ultrasonic impedance is lessthan the impedance reset threshold 2228). If these conditions are met,the generator may, at 2224, release the filtered Condition Set latch;reset the debounce timer (e.g., TIMER X in FIG. 22); reset the latchtimer; reset the load timer (e.g., time above impedance period), resetthe baseline frequency latch; and set the frequency delta equal to zero.Logic flow 1400′ may return an indication that the filtered ConditionSet is not met.

Referring now back to 2214, if the filtered Condition Set latch is notset, the generator may determine if the unfiltered condition set is metat 2216 (e.g., based on the return of 2212). If not, the debounce timermay be reset at 1410 and the logic flow 1400′ may return an indicationthat the filtered Condition Set is not met. If yes, the generator mayincrement the debounce timer at 1408. At 1414, the generator maydetermine whether the debounce timer is greater than a required timebefore trigger parameter 1412, as described above. If so, algorithm1400′ may proceed along the YES path, latching the filtered conditionset latch at 1416 and returning an indication that the filteredCondition Set is met.

FIG. 60 is a logic flow diagram for implementing one form of theunfiltered condition set logic 2212 shown in FIG. 59 that may beimplemented in one form of a generator. At 2232, the generator maydetermine whether a local frequency slope is less than a frequency slopethreshold parameter 1404. In some forms, the frequency slope thresholdparameter may depend on a power level delivered by the generator, asdescribed above. If the local frequency slope is less than the frequencyslope threshold parameter 1404, the generator may, at 2236, determinewhether the local resonant frequency is less than a frequency thresholdparameter 1406. If so, the algorithm 2212 may return an indication thatthe unfiltered Condition Set is met. In some forms, the conditions 2232,2236 may be implemented in a logical “OR” manner instead of the logical“AND” manner shown. For example, after a determination that the localfrequency slope is less than the frequency slope threshold parameter1404, the algorithm may return an indication that the unfilteredCondition Set is met. Similarly, upon a determination that the localfrequency slope is not less than the frequency slope threshold parameter1404, the algorithm may evaluate the resonant frequency and frequencythreshold parameter 1406 at 2236.

If the conditions evaluated at 2232 and 2236 are not met (in whateverlogical arrangement is used), the generator may determine, at 2240,whether the difference between the baseline frequency (e.g., as set at2196) and the local resonant frequency (e.g., the frequency delta)exceeds a baseline deviation threshold parameter 2242. If yes, thealgorithm 2212 may return an indication that the unfiltered ConditionSet is met. If no, the algorithm 2212 may return an indication that theunfiltered Condition Set is not met.

In certain forms, generators, such as 30, 500, 1002, and/or ultrasonicsurgical instruments, such as 100, 120, 1004, may be implemented withone or more Condition Sets that utilize load events to arm Response Settriggers. For example, the generator may detect load events, asdescribed herein. A load event may occur, for example, when the load onthe ultrasonic blade experiences a change (e.g., a sudden or rapidchange). Physical conditions that may cause a load change include, forexample, the opening and/or closing of the clamp arm, a sudden drop ofthe ultrasonic blade through tissue, etc. In various forms, upondetection of a load event, Response Set triggers may be armed, orcapable of being triggered upon the occurrence of other conditions inthe corresponding Condition Set. When no load event is detected, theResponse Set triggers may be disarmed, or incapable of being triggeredeven upon occurrence of other conditions in the corresponding ConditionSet. The existence of a load event may serve as an alternate indicatorof the types of physical conditions to be detected by various ConditionSets (e.g., changes in tissue state, such as tissue separation,desiccation, etc.). Accordingly, Condition Sets that utilize load eventtriggers are less likely to return false positives (e.g., situationswhere the Condition Set is met, but the underlying physical condition isnot present). As a result, Condition Sets utilizing load events may alsoutilize lower and more sensitive thresholds for frequency slopethresholds 1404, frequency thresholds 1406, etc.

According to various forms, load events may be detected by examiningchanges in the frequency slope over time. FIG. 61 is a graphicalrepresentation of a frequency slope 2302 and a second time derivative offrequency 2304 for an ultrasonic blade illustrating a pair of loadevents. The load events are apparent in frequency slope plot 2302 atfeatures 2305 and 2306 and in second time derivative plot 2304 atfeatures 2307 and 2308. The blade that generated the characteristicsillustrated in FIG. 61 was activated unloaded at about ½ seconds,clamped at about 1½ seconds, and unclamped at about 3½ seconds, asindicated on the horizontal axes. The clamping and unclamping maycorrespond to the load events indicated by 2305, 2307 and 2306, 2308. Itwill be appreciated that the frequency slope itself may be affected byboth thermal events (e.g., changes in the temperature of the blade) andload events. This is illustrated by FIG. 61, as the frequency slope plot2302 comprises various changes in addition to the features 2305, 2306.In contrast, the second time derivative plot 2304 is approximatelyconstant except for dramatic changes at the features 2307, 2308.

In view of this, certain forms detect the presence of a load event byexamining changes in frequency slope over a rolling window. For example,a present or local frequency slope is compared to a past frequency slopeoffset from the local frequency slope by a window offset time.Continuing results of the comparison may be referred to as a rollingdelta. The window offset time may be any suitable time and, in certainforms, may be about 100 msec. When the rolling delta exceeds a frequencyslope threshold parameter, a load event may be detected. In certainforms, load events beginning when the blade is unloaded may not beconsidered (e.g., Response Set triggers may not be armed). For example,before examining the frequency slope over the rolling window, thegenerator may first detect an increase in ultrasonic impedance above animpedance threshold. (In some forms, the impedance threshold must beheld for a time above impedance threshold parameter before the generatorwill detect a load event.) The impedance threshold may be any suitablevalue and, in certain forms, is between about 5 ohms and about 260 ohms,with a resolution of about 5 ohms. In one example form, the impedancethreshold is about 100 ohms. The increase in ultrasonic impedance abovethe threshold may indicate, for example, that the clamp arm is closed,therefore, making a load event more likely.

FIG. 62 is a graphical representation of a frequency slope 2310, asecond time derivative of frequency 2312, and a rolling delta 2314demonstrating a load event. Feature 2316 of the rolling delta plot 2314indicates that the rolling delta exceeded the frequency slope thresholdparameter, thus indicating a load event. FIG. 63 is graphicalrepresentation of another form of a frequency slope 2318, a second timederivative of frequency 2320 and a rolling delta 2322 demonstratinganother load event. Feature 2324 in the rolling delta plot 2322, feature2326 in the second derivative plot 2320 and feature 2328 in thefrequency slope plot 2328 indicate the load event.

FIG. 64 is a logic flow diagram for implementing one form of analgorithm 2330 applying a Condition Set including a load event triggerthat may be implemented in one form of a generator. At 2332, thegenerator may determine whether a load event is occurring. Furtherexamples of how the generator may determine whether a load event isoccurring are provided herein with respect to FIG. 65. If no load eventis occurring, the generator may continue to test for a load event at2332. If a load event is occurring, the generator may “arm” a relevantResponse Set at 2334. Arming the Response Set may comprise enabling theResponse Set to be triggered when its corresponding Condition Set ismet. At 2336, the generator may determine if the local ultrasonicimpedance is below an impedance reset threshold parameter. The impedancereset threshold parameter may be an impedance level at which thegenerator concludes that the load event is concluded. If the localultrasonic impedance is below the impedance reset threshold parameter,the generator may disarm the Response Set at 2342. If the localultrasonic impedance is not below the impedance reset threshold, thenthe generator (e.g., 30, 500, 1002) may determine of the Condition Setparameters are met at 2338. If the Condition Set is met, the generatormay trigger the appropriate Response Set at 2340.

FIG. 65 is a logic flow diagram for implementing one form of analgorithm 2332 for determining whether a load condition exists in asurgical instrument. At 2342, the generator may determine if the localultrasonic impedance of the ultrasonic blade/transducer system exceedsan impedance threshold. For example, ultrasonic impedance exceeds thethreshold, it may indicate closure of the clamp arm. If no, thealgorithm 2332 may return an indication that there is no load event at2334. If the local ultrasonic impedance exceeds the impedance threshold,the generator may determine at 2346 whether the frequency rolling deltais greater than a frequency slope threshold parameter. If yes, thealgorithm 2332 may return a load event 2348. If no, then the algorithm2344 may return no load event.

In various example forms, Condition Sets that utilize load events to armResponse Set triggers may be utilized in the context of the logic flowdiagrams 1200, 1300, 1400 of FIGS. 20-22 described above. For example,FIG. 66 is a logic flow diagram of one form of a signal evaluationtissue algorithm portion 1300″ of the tissue algorithm 1200 shown inFIG. 20 considering a Condition Set utilizing a load event to armResponse Set triggers. In various forms, the signal evaluation tissuealgorithm 1300″ may operate in a manner similar to that of the algorithm1300 described above, with several differences. For example, inalgorithm 1300″, the Signal Evaluation/Monitoring function 1308 may beperformed prior to the time to wait comparison at 1306, although it willbe appreciated that these actions may be ordered in any suitable orderfor any of the algorithms 1300, 1300′, 1300″ described herein.Additionally, the Signal Evaluation/Monitoring function 1308 may alsocapture a local ultrasonic impedance (|Z|_(Mot)) and the rolling delta(F_(slope_delta)), that may be passed to the various condition setevaluation algorithms 1400, as described herein. For example, thealgorithm 1300 may pass as arguments the local ultrasonic impedance, therolling delta, the local frequency slope (F_(slope)) and the localresonant frequency (F_(t)).

FIG. 67 is a logic flow diagram of an algorithm 1400″ for evaluatingcondition sets for the signal evaluation tissue algorithm 1300″ shown inFIG. 66 that may be implemented in one form of a generator. At 2352, thegenerator may determine whether a maintain status flag 2354 is set. Ifnot, then the Response Set corresponding to the Condition Set of thealgorithm 1400″ may be armed at 2358. In certain forms, arming theResponse Set at 2358 may effectively disable load monitoring. If themaintain status flag 2354 is set, a load monitoring algorithm 2356 maybe executed. The load monitoring algorithm 2356 may either arm, or notarm, the Response Set trigger depending on whether a load event isdetected. Additional details of the load monitoring algorithm 2356 areprovided below with respect to FIG. 68. At 2360, the generator mayimplement logic for determining if an unfiltered Condition Set is metfor the evaluated Condition Set. Logic 2360 is described in more detailbelow with respect to FIG. 69 and may return a “true” or “false”response.

At 2368, the generator may determine whether a filtered Condition Setlatch is set. The filtered Condition Set latch may be set, as describedbelow, when the filtered Condition Set is met, for example, so as toensure that the filtered Condition Set is indicated to be set for athreshold period of time. If the filtered Condition Set latch is set,the generator may increment a latch timer at 2365 and determine whetherthe unfiltered Condition Set is met at 2366. If the unfiltered conditionset is met, then the logic flow 1400″ may return an indication that thefiltered Condition Set is met.

If the unfiltered condition set is not met at 2366, the generator mayevaluate the whether the Condition Set is still met at 2368. Forexample, the generator may determine (i) whether the filtered ConditionSet latch timer has exceeded a minimum latch timer 1422; and (ii)whether the frequency slope is greater than a cross-back frequency slopethreshold 1424. If these conditions are met, the generator may, at 2378,release the filtered Condition Set latch; reset the debounce timer(e.g., TIMER X in FIG. 22); reset the latch timer; reset the load timer(e.g., time above impedance period), and disarm the Response Settrigger. Logic flow 1400″ may return an indication that the filteredCondition Set is not met.

Referring now back to 2362, if the filtered Condition Set latch is notset, the generator may determine if the unfiltered condition set is metat 2364 (e.g., based on the return of 2360). If not, the debounce timermay be reset at 1410 and the logic flow 1400″ may return an indicationthat the filtered Condition Set is not met. If yes, the generator mayincrement the debounce timer at 1408. At 1414, the generator maydetermine whether the debounce timer is greater than a required timebefore trigger parameter 1412, as described above. If so, algorithm1400″ may proceed along the YES path, latching the filtered conditionset latch at 1416 and returning an indication that the filteredCondition Set is met.

FIG. 68 is a logic flow diagram of one form of a load monitoringalgorithm 2356 that may be implemented in one form of a generator, asshown in FIG. 67. The load monitoring algorithm 2356 may receive asinput the local ultrasonic impedance (|Z|_(Mot)) and the rolling delta(F_(slope_delta)). As output, the algorithm 2356 may either arm, or notarm, the relevant Response Set. At 2380, the generator may determine ifthe ultrasonic impedance exceeds the impedance threshold 2381. If so,the generator may increment a load timer at 2382. The load timer may actto debounce the local ultrasonic impedance. For example, the generatormay not consider the ultrasonic impedance to be higher than thethreshold 2381 unless it is higher than the threshold for a predeterminenumber of ticks of the timer.

At 2384, the generator may determine whether the load timer is greaterthan a required time above threshold parameter 2386. If yes, thegenerator may arm the load trigger at 2396 and proceed to 2398. Forexample, the load trigger may be armed when a load is indicated by theultrasonic impedance. If no at 2384, the generator may proceed directlyto 2398 without arming the load trigger. At 2398, the generator maydetermine whether the load trigger is armed. If no, the load setmonitoring algorithm 2356 may return with the both the load trigger andthe Response Set trigger unarmed. If yes, the generator may determine at2400 whether the rolling delta exceeds the frequency slop thresholdparameter 2402. If no, then the algorithm 2356 may return with the loadtrigger set and the Response Set trigger unarmed. If yes, then theResponse Set trigger may be armed at 2404 and the algorithm 2356 mayreturn. Referring back to 2380, if the ultrasonic impedance is not abovethe impedance threshold, the generator may reset the load timer at 2388.At 2390, the generator may determine whether the ultrasonic impedance isless than an impedance reset threshold parameter 2392. If yes, then thegenerator may disarm the Response Set trigger and load trigger at 2394.If no, the generator may proceed to 2398 as described above.

FIG. 69 is a logic flow diagram of one form of an unfiltered conditionset logic 2360 shown in FIG. 67 that may be implemented by one form of agenerator. At 2406, the generator may determine whether a localfrequency slope is less than a frequency slope threshold parameter 1404.In some forms, the frequency slope threshold parameter may depend on apower level delivered by the generator, as described above. If the localfrequency slope is less than the frequency slope threshold parameter1404, the generator may, at 2408, determine whether the local resonantfrequency is less than a frequency threshold parameter 1406. If yes, thegenerator may determine at 2410 whether the load trigger and theResponse Set trigger are armed. If yes, the algorithm 2360 may return anindication that the unfiltered Condition Set is met. If no, thegenerator may determine whether the filtered Condition Set is latch isset at 2412. If yes, the algorithm 2360 may return an indication thatthe unfiltered Condition Set is met. If no at any one of 2406, 2408 or2412, the algorithm 2360 may return an indication that the unfilteredCondition Set is not met.

In some forms, the conditions 2406 and 2408 may be implemented in alogical “OR” manner instead of the logical “AND” manner shown. Forexample, after a determination that the local frequency slope is lessthan the frequency slope threshold parameter 1404, the algorithm 2360may jump directly to 2410. Similarly, upon a determination that thelocal frequency slope is not less than the frequency slope thresholdparameter 1404, the algorithm may evaluate the resonant frequency andfrequency threshold parameter 1406 at 2408.

Various forms of algorithms 1400, 1400′ and 1400″ for evaluatingCondition Sets for the signal evaluation tissue algorithms 1300, 1300′,1300″ are described. It will be appreciated that any number of ConditionSet evaluation algorithms may be implemented with any of the signalevaluation tissue algorithms 1300, 1300′, 1300″ described herein. Forexample, in certain forms, the generator may implement a Condition Setevaluation algorithm 1400, as described herein above, in conjunctionwith a Condition Set evaluation algorithm 1400″ utilizing a load eventtrigger. Any suitable combination of algorithms 1300, 1300′, 1300″,1400, 1400′, 1400″ may be used.

In some example forms of the ultrasonic surgical instrument andgenerator, current is maintained so as to be relatively constant. Thismay establish a substantially constant displacement for the ultrasonicblade that, in turn, establishes a substantially constant rate oftissue-effecting activity. In some forms, the current is maintained,even over changing mechanical loads, where the mechanical load isreflected by the ultrasonic impedance. To achieve this, differences inmechanical load may be compensated for substantially by modulatingapplied voltage.

As described herein, to operate efficiently (e.g., minimize waste heatat the transducer), the surgical instrument (e.g., blade and transducercombination) may be driven at or near the system's resonant frequency.The frequency of the system may be determined via a phase differencebetween the current and voltage signals. As described herein, theresonant frequency of the system changes with thermal changes. Forexample, the additional of thermal energy (e.g., heat) results in asoftening of the blade and/or other system components, thereby changingthe system's resonant frequency. Accordingly, the generator, in someexample forms, implements two control loops. A first loop maintains asubstantially constant current across varying loads, while a secondcontrol loop tracks the system resonant frequency and modifies thedriving electrical signals accordingly.

As described herein, various algorithms for use with ultrasonic surgicalinstruments approximate physical conditions of the instrument (e.g., theultrasonic blade thereof) based on the electrical signals provided tothe instrument. For example, with respect to FIGS. 58 and 65, closure ofthe clamp arm is determined by monitoring ultrasonic impedance. It willbe appreciated, however, that in any of the forms described herein,closure of the clamp arm may be alternatively determined in any suitablemanner, for example, from any suitable electrical signal provided to theinstrument and/or derivations thereof. In some example forms wherecurrent is kept substantially constant, the value of the voltage signalis proportional to ultrasonic impedance. Therefore, the variousultrasonic impedance thresholds described herein may alternately beimplemented as voltage thresholds. Similarly, where current issubstantially constant, power or energy delivered to the blade will alsobe proportional to ultrasonic impedance and corresponding changes inpower, energy, changes in voltage, power or energy with respect to time,etc., may also indicate clamp arm closure. Also, as illustrated herein,when the clamp arm initially closes, the temperature of the ultrasonicblade may drop as it comes into contact with cool tissue. Accordingly,blade closure may alternately be detected by monitoring for a drop inblade temperature, indicated either by a rise in the resonant frequencyof the blade and/or one of the other methods described herein. Also, insome forms, closure of the clamp arm may be determined based ondetecting activation of a closure trigger and/or closure control.Various forms may detect clamp arm closure utilizing combinations ofsome or all of the electrical signal properties described.

Also, for example, load events are described herein, for example, withrespect to FIG. 65. In FIG. 65 and the associated description loadevents are detected based on a frequency rolling delta. Various otherqualities of the electrical signals provided to the instrument may alsobe used to indicate a load event. For example, the physical changesindicated by the frequency rolling delta may also be indicated by thevoltage signal, a change in the voltage signal with respect to time, theultrasonic impedance including the slope thereof, a second derivative offrequency, current, changes in current with respect to time, etc.Additionally, changes in the temperature of the blade, as describedherein, are determined based on detecting changes in the frequencyslope. Additional electrical signal properties that may vary based onblade temperature may include, for example, the slope of the powerand/or energy provided to the blade.

According to various forms, an ultrasonic instrument, such as theinstruments 100, 120, 1004 may be driven according to a controlalgorithm that involves driving the instrument sequentially at differentpower levels. For example, when the ultrasonic surgical instrument isactivated, it may be driven at a first power level. For example, agenerator (e.g., generators 30, 500, 1002 and/or an internal generator)may provide a drive signal at a first power level. After the expirationof a first period, the generator may provide a second drive signal at asecond power level less than the first power level. In someapplications, the first, higher power level may serve to separate theinner muscle layer of a vessel from the adventilia layer, as describedherein.

FIG. 71 is a logic flow diagram of one form of an algorithm 3021 fordriving an ultrasonic instrument sequentially at two power levels. FIG.70 is a chart illustrating a power or displacement plot for one exampleimplementation of the algorithm of FIG. 71. The algorithm 3021 may beimplemented by a generator, such as 30, 500, 1002 and/or an internalgenerator, to drive an ultrasonic instrument such as 100, 120, 1004. InFIG. 70, vertical axis 3002 corresponds to a displacement of the endeffector blade. The horizontal axis 3004 corresponds to time in seconds.The algorithm 3021 is described herein as implemented by a generator,such as one of generators 30, 500, 1002 herein, it will be appreciatedthat the algorithm 3021 may alternately be implemented by an instrument,such as 100, 120, 1004 (e.g., by a control circuit 2009 thereof).

At 3020, the generator may receive a trigger signal provided by aclinician. The trigger signal may be provided in any suitable manner.For example, in some forms, the clinician provides the trigger signalutilizing a button or other input device on the instrument itself (e.g.,buttons 312 a, 1036 a, 1036 b, 1036 c, footswitches 434, 1020, etc.). At3022, the generator may activate the instrument by providing a firstdrive signal. Referring to FIG. 70, activation of the instrument isindicated at 3006. The first drive signal corresponds to a first levelof power provided to the end effector of the instrument. At 3024, thegenerator maintains the first drive signal for a first period. The endeffector displacement corresponding to the first drive signal isindicated in FIG. 70 at 3009. As illustrated in the example of FIG. 70,first power level corresponds to an end effector displacement of between60 and 120 microns, such as about 75 microns. The first power level maybe selected to separate the inner muscle layer of a vessel from theadventilia layer and/or to provide other tissue effects tending toimprove the dissection and/or sealing process. In some forms, the firstdrive signal may also provide off-resonance, as described herein, tofurther aid in the separation of the inner muscle layer of a vessel fromthe adventilia layer

The generator determines whether the first period has expired at 3026.The first period may be measured in any suitable manner. For example, insome forms, the first period is a set time period that expires after apredetermined amount of time has passed since the activation of theinstrument. This is the case in the example shown in FIG. 70, whereinthe first period is one second. Also, in some forms, the first periodexpires when a particular tissue change of state occurs. Any of thechanges in tissue state described herein may indicate the end of thefirst period and, for example, any of the algorithms described hereinfor detecting a change in tissue condition may be utilized. For example,in some forms, the end of the first period may be indicated by a changein the impedance of the transducer.

When the first period expires, the generator provides a second drivesignal at a second power level at 3028. In the example of FIG. 70, thetransition from the first to the second drive signal is indicated at3007. The end effector displacement at the second drive signal isindicated in FIG. 70 to be between about 20 and 60 microns, such asabout 37.5 microns. Although the second drive signal is indicated inFIG. 70 to be a continuous signal, it will be appreciated that, in someforms, the second drive signal is a pulsed drive signal, for example, asdescribed herein. The second drive signal may be provided to theinstrument until any suitable endpoint. For example, referring to FIG.70, the completion of tissue dissection is indicated at 3008.Deactivation of the instrument is indicated at 3010. In some forms,tissue dissection may be detecting using any of the algorithms fordetecting tissue state changes described herein. In some forms, thegenerator may automatically deactivate the instrument either atdissection point 3008 and/or thereafter (e.g., a predetermined timeperiod thereafter).

The algorithm 3021 may improve the performance of the instrumentrelative to simply activating the instrument at a single power level.FIG. 72 is a chart illustrating burst pressures obtained with a surgicalinstrument similar to the instrument 1004 operated according to thealgorithm of FIG. 71 (3030) and operated by activating the instrument1004 at a single power level (3032). In the example of FIG. 72, plot3032 corresponds to the instrument 1004 activated at a single powerlevel corresponding to the second power level of the algorithm 3021.Both the trials for the algorithm 3021 and those at the single powerlevel were conducted on 5-7 mm porcine ceratoid arteries. As can beseen, the algorithm 3012 lead to higher burst pressures, which maycorrespond to higher quality seals and transections. FIG. 73 is a chartillustrating transection times obtained for the trials indicated in FIG.72. As illustrated, the algorithm 3021 may provide superior transectiontimes.

In use, the algorithm 3021 has a potential for misuse by clinicians. Forexample, FIG. 74 is a chart 3040 illustrating a drive signal patternaccording to one form of the algorithm 3021. In FIG. 74, the verticalaxis 3042 corresponds to a power level provided and the horizontal axis3004 corresponds to time. The first and second power levels areindicated on the axis 3042 as “5” and “1,” respectively. For example,when implemented on the GEN 11 generator available from EthiconEndo-Surgery, Inc. of Cincinnati, Ohio, “5” may correspond to powerlevel “5” and “1” may correspond to power level “1.” As illustrated, theclinician has activated (3006) and deactivated (3010) the instrumentseveral times in succession without completing tissue transection. Asillustrated, the clinician deactivated the instrument near the beginningof the second (lower power) drive signal in order to reactivate theinstrument and reestablish the first (higher power) drive signal. Itwill be appreciated that this type of use may prevent the algorithm 3021from operating as designed. In some forms, the algorithm 3021 may bemodified to implement a rest time between a deactivation 3010 and asubsequent activation 3006.

FIG. 75 is a logic flow diagram of another form of the algorithm 3021′implementing a rest time between a deactivation of the instrument and asubsequent activation. The algorithm 3021′ may be implemented by agenerator, such as 30, 500, 1002 and/or an internal generator, to drivean ultrasonic instrument such as 100, 120, 1004. After receiving thetrigger signal at 3020, the generator may determine at 3050 if a resttime has passed since a most recent activation of the instrument. Invarious forms, the rest time is selected to correspond to an amount oftime that would allow the ultrasonic blade and/or tissue to return to arest state. In one example form, the rest time is four seconds. If therest time has passed, then the algorithm 3021′ may proceed to actions3022, 3024, 3026 and/or 3028 as described herein above. If the rest timehas not passed at 3050, then the generator may, at 3052, provide theinstrument with a drive signal at the second power level (e.g., thelower of the power levels of the algorithm 3021′). In this way, if therest period has not passed since a previous deactivation, the algorithm3021′ may continue at the point where it left off at the deactivation.

FIG. 76 is a chart illustrating a drive signal pattern according to oneform of the algorithm 3021′. The clinician may activate the instrumentat 3056. When the second drive signal is provided, the cliniciandeactivates the instrument at 3058. For example, the deactivation 3058may occur before tissue sealing and transection is complete. At 3660,the clinician reactivates the instrument, for example by generating atrigger signal as described herein above. As illustrated, however, therest time did not pass before the reactivation at 3660. Accordingly, thegenerator, at 3660, provides a drive signal at the second power level.After the deactivation at 3062, however, the rest time did pass beforethe reactivation at 3064. Accordingly, the generator provides a drivesignal at the first power level and the algorithm 3021′ proceeds asshown in FIG. 70.

In various forms, the algorithm 3021′ may be implemented utilizing analternate logic condition in place of the rest time. For example,instead of determining whether the rest time has expired at 3050, thegenerator may determine whether the alternate logic condition has beenmet. The alternate logic condition may be any suitable conditionincluding, for example, an indicator of a state of the instrument and/ortissue being acted upon. In some forms, the logic condition may be, orbe related to, a temperature of the end effector. For example, thealternate logic condition may be based on the resonant frequency of theultrasonic drive system and end effector, as indicated by the frequencyof the drive signal. If the frequency is above a threshold value(indicating that the temperature of the end effector temperature isbelow a threshold value), then the algorithm 3021′ may proceed toactions 3022, 3024, 3026, 3028 as described. The frequency of the drivefrequency may be measured in any way including, for example, thosedescribed herein above with respect to FIG. 21 above. In anotherexample, the alternate logic condition may be based on the impedance ofthe ultrasonic transducer, which may serve as another proxy for endeffector temperature, as described herein above with respect to FIGS.10-13. Also, in some forms, the temperature of the end effector may bemeasured by a temperature probe at the end effector, such at thetemperature probe 3070 positioned at the end effector 1026 of FIG. 16A.

FIG. 77 is a logic flow diagram of another form of the algorithm 3021″implementing a third drive signal. The algorithm 3021″ may beimplemented by a generator, such as 30, 500, 1002 and/or an internalgenerator, to drive an ultrasonic instrument such as 100, 120, 1004. Thegenerator may perform actions 3020, 3022, 3024, 3026, 3028 as describedabove with respect to FIG. 71. After providing the second drive signalat 3028, however, the generator may maintain the second drive signal at3070 until the expiration of a second period at 3072. At the expirationof the second time period, the generator may provide a third drivesignal at 3074. The third drive signal is at a third power that may begreater than the second power and less than the first power. Forexample, in one example form, the second power level is 45% of the firstpower level. The third point level may be, for example 100%, 75%, etc.of the first power level. The first and second periods may be, forexample, 1.5 seconds and twelve seconds, respectively. It will beappreciated that the algorithm 3021″ may be implemented with a rest timeperiod, for example, as the algorithm 3021′. For example, the actions3070, 3072 and 3074 may be performed after action 3028 as illustrated inFIG. 75

In various forms, the algorithm 3021″ may lead to higher burst pressuresand shorted transection times relative to the algorithm 3021 illustratedin FIG. 71. For example, FIG. 79 is a chart illustrating burst pressuresobtained with a surgical instrument similar to the instrument 1004operated according to the algorithm 3021 versus the surgical instrumentoperated according to the algorithm 3021″. As illustrated, the burstpressure for the algorithm 3021″ are higher than with the algorithm3021. Similarly, FIG. 80 is a chart illustrating transection timesobtained for the trials indicated in FIG. 79. As illustrated,transection times for the algorithm 3021″ are lower than for thealgorithm 3021. Also, in some forms where the algorithm 3021″ isimplemented in a conjunction with another algorithm for providingfeedback (e.g., a response set) upon detecting a change in tissue state(e.g., a condition set), providing the third, higher power drive signalmay increase the effective of the algorithms described herein fordetecting a change in tissue state.

In some forms, the algorithms 3021, 3021′, 3021″ may be implemented inconjunction with various other algorithms described herein. For example,any of the algorithms 3021, 3021′, 3021″ may be implemented inconjunction with a condition set and/or response set based on a measuredcharacteristic of the instrument and/or tissue acted upon by theinstrument. For example, the algorithms 3021, 3021′, 3021″ may beimplemented with one of the algorithms described herein above withrespect to FIGS. 15A-15C, FIGS. 20-22, FIGS. 57-60, etc. When acondition set indicates a tissue condition, the corresponding responseset may be executed on top of the algorithms 3021, 3021′, 3021″. Forexample, when a triggered condition set calls for feedback, the feedbackmay be provided while the algorithm 3021, 3021′, 3021″ continues. Also,for example, when a triggered condition set calls for a change to thedrive signal, the generator may deviate from the algorithm 3021, 3021′,3021″ in accordance with the triggered response set.

FIG. 81 is a logic flow diagram of one form of an algorithm 3100implementing an initial clamping period. The algorithm 3100 may beimplemented by a generator, such as 30, 500, 1002 and/or an internalgenerator, to drive an ultrasonic instrument such as 100, 120, 1004. At3102, the generated may receive an activation request, for example, asdescribed herein above with respect to the activation request 3020. At3104, the generator may provide feedback indicating that the instrumenthas been activated. The feedback may be audible, visual and/or tactilefeedback as described herein. When the feedback is provided, however,the instrument is not yet activated. In this way, the algorithm 3100 mayprovide time for the end effector to compress tissue prior to activatingthe instrument so as to increase the efficacy of transection andsealing. At 3106, the end effector may determine whether a first timeperiod has expired. The first time period may be, for example, a fewseconds. When the first time period has expired, the generator mayactivate the instrument and begin executing a control algorithm. Thecontrol algorithm may be any suitable algorithm including, for example,any of the algorithms 3021, 3021′, 3201″. For example, referring to FIG.71, actions 3104, 3106 would be performed after receiving the triggersignal 3020. Action 3022 would be performed to correspond to 3108.

FIG. 82 is a logic flow diagram of another form of an algorithm 3120implementing an initial clamping period. The algorithm 3021″ may beimplemented by a generator, such as 30, 500, 1002 and/or an internalgenerator, to drive an ultrasonic instrument such as 100, 120, 1004. Forexample, the algorithm 3120 may implement the initial clamping period inconjunction with a step function, such as the step function describedherein above with respect to FIGS. 6-8. Referring again to FIG. 82, thegenerator may perform actions 3102, 3104, and 3106 as described hereinwith respect to FIG. 81. At 3122, the generator may provide a firstdrive signal 3122 at a first level. The first level may correspond to acurrent, a power, an end effector displacement, etc. When a second timeperiod has expired at 3124, the generator provides a second drive signalat 3126. The second drive signal corresponds to a current, power and orend effector displacement at a level higher than that of the firstlevel. The second drive signal may be maintained until the generatordetects a change in tissue state such as, for example, a drop in thefrequency slope below a threshold frequency slop at 3128. Upon theoccurrence of such an event, the generator may provide a third drivesignal at 3130. The third drive signal may be maintained, for example,until an additional change in the state of the tissue (e.g.,transection), for example, as determined by an algorithm, such as thosedescribed above with respect to FIGS. 15A-15C, FIGS. 20-22, FIGS. 57-60,etc.

FIG. 83 is a chart illustrating a drive signal pattern according to thealgorithm 3120. The vertical axis 3132 corresponds to drive signalcurrent while the horizontal axis 3134 corresponds to time. Theactivation signal is received at 3092. The first time period isrepresented by 3096. The second time period with the first drive signalis indicated at 3097. The second drive signal is provided at 3098 untilthe frequency slope threshold is met at 3135, upon which the third drivesignal is indicated by 3099. Transection is indicated at 3008, anddeactivation at 3094.

As described above, any of the algorithms described herein including,3021, 3021′, 3021″, 3100, 3120, etc., may be implemented in conjunctionwith an algorithm for implementing a condition set and response set. Thecondition set, for example, may be true based on the presence or absenceof a particular state of the ultrasonic instrument and/or tissue actedupon by the ultrasonic instrument. The response set may define actionsto be taken by the instrument and/or the generator upon the conditionset being true. In some forms, various condition sets may be estimatedutilizing one or more multi-variable models. Examples of multi-variablemodels may include, for example, neural network models, geneticalgorithm models, classification tree algorithm models, recursiveBayesian models, etc.

One suitable type of multi-variable model comprises a neural network.Neural networks may be effective for recognizing complex patterns ininput variables, which may make them well suited to detect conditionsets based on tissue state (e.g., whether transection has occurred,whether sealing has occurred, etc.). FIG. 84 is a diagram showing anexample neural network 3150. The neural network 3150 comprises a groupof interconnected nodes 3152, 3154, 3156 referred to as neurons.Connections between different neurons indicate how data is passedthrough the network. Input neurons 3152 are assigned values from inputdata (e.g., various parameters of the surgical instrument, the drivesignal, etc.). In various forms, the input variables are scaled tovalues between zero and one. The values of the input neurons 3152 (e.g.,the input variables) are then utilized to calculate values of varioushidden neurons 3154, which are, in turn, used to find the value of oneor more output neurons 3156. The value of the output neuron 3156 maytrigger (or not trigger) a response set such as, for example, feedbackand/or changes to the drive signal. In practice, the number ofrespective input nodes 3153, hidden nodes 3154 and output nodes 3156 mayvary, sometimes considerably, from what is shown in FIG. 84. In variousforms, a neural network is operated on a data cycle. During each cycle,input values are provided to the input neurons 3152 and output valuesare taken at the output node 3156.

Neural networks may be fully connected, as shown in FIG. 84, meaningthat each input neuron 3152 is connected to each hidden neuron 3154.Some forms may utilize a neural network that is not fully connected. Forexample not all of the input nodes may be connected to each hiddenneuron 3154. Values for the hidden nodes 3154 may be determinedaccording to an activation function. In various forms, the outputs ofthe activation function range from 0 to 1. For example, the outputfunction may be selected to generate outputs between 0 and 1 or, in someforms, results of the output function may be scaled. In some forms, itis advantageous to select functions that are continuous anddifferentiable. This may facilitate training of the neural network. Forexample, back-propagation training utilizing a gradient method mayrequire computing partial derivatives of the output function, which maybe simplified when the optimization functions are continuous anddifferentiable. One example of such a function that may be utilized asthe activation functions is the sigmoid function, as indicated byEquation (8) below:x=ω ₁ξ₁+ω₂ξ₂+ω₃ξ₃+ . . . +θ  (8)In Equation (8), ξ corresponds to the values of the input neurons, ωcorresponds to the weights given to each input, θ corresponds to aconstant. When the neural network is fully connected, the values of allinput neurons are passed to all hidden neurons, meaning the activationfunction for each hidden neuron will include a term ξ corresponding toeach input node. The weights given to each input (ω) may be unique foreach hidden neuron and/or each input value. The constant θ may also beunique for each hidden neuron 3154. The results at each node may begiven by Equations (9) and (10) below:

$\begin{matrix}{{\sigma(x)} = \frac{1}{1 + e^{- x}}} & (9)\end{matrix}$FIG. 85 is a plot of one example implementation of Equation (9),demonstrating that the function is continuous and differentiable.O=σ(x)  (10)The output of the sigmoid function is illustrated in FIG. 86. Forexample, the output (O) may be calculated from the weighted sum of theinput neurons plus theta (e.g., Equation (8)) applied to Equation (9).

In various forms, each hidden neuron has I inputs, which is equal to thenumber of inputs to the neural network. If there are J hidden neurons3154, then there are I×J unique values for omega (ω) and J unique valuesfor theta (θ). In some forms, the output neuron(s) 3156 may utilize thesame activation equation. Accordingly, there may be J×K unique omega (ω)values connecting the hidden neurons 3154 to the output neuron 3156,where K is the number of output neurons, and K unique values of theta(θ) for the output node(s) 3156.

The output of the neural network may indicate the truth of falsity of acondition set comprising one or more conditions of the ultrasonicsurgical instrument, tissue acted upon by the surgical instrument, orsome combination thereof. For example, a neural network may be used tomodel a condition set indicating whether to provide feedback indicatingtissue transection at or near the separation point. For example, in someforms, the output of the neural network may indicate whether 80%transection has been achieved. Any suitable number or type of neurons3152, 3154, 3156 may be used. For example, the neural network 3150 maycomprise twelve input neurons 3152, (I=12), four hidden neurons (J=4),and one output neuron (K=1). The data cycle may be 10 milliseconds.Accordingly, values for the 12 inputs may be fed into the network 3150,and results calculated, every 10 milliseconds.

Input variables (e.g., variables corresponding to the input nodes 3152)may comprise any variables that could, in some circumstances, affect thevalue of an output node 3156. The example input variables describedbelow may be utilized in a neural network, such as 3154, having anoutput node or nodes corresponding to any suitable ultrasonicinstrument-related value such as, for example, 80% transection. It willbe appreciated that the input variables described herein may also beused any other suitable type of model including, for example, geneticalgorithm models, classification tree algorithm models, recursiveBayesian models, etc.

In some forms, input variables corresponding to input nodes 3152 includevariables describing the operation of the surgical system during thetreatment of tissue. A tissue treatment, for example, may begin when thesurgical system is activated on tissue. Example tissue treatment inputvariables are described below:

An elapsed time since activation input variable may represent a timesince the activation of the instrument (e.g., at the beginning of atissue treatment). Time may be measured in any suitable incrementsincluding, for example, 10 milliseconds (0.010 seconds) beginning atinstrument activation (e.g., 0.00 seconds). In some forms, the elapsedtime since activation is measured and stored by the generator.

Different variables may be utilized to describe the operation of theultrasonic transducer or hand piece including, for example, a voltagedrop across the transducer, a current drawn by the transducer, and animpedance of the transducer. Values for these and similar variables maybe captured and stored (e.g., by the generator) at any suitableinterval. For example, voltage current and/or impedance values may becaptured at an interval equal to the data cycle of the neural network3150.

Additional input variables describe different permutations of voltage,current and/or impedance of the transducer over predetermined timeperiods. For example, averages of voltage, current or impedance may betaken over the entire activation period (e.g., described by the elapsedtime since activation). Also, in some forms, averages of voltage,current or impedance are taken over a predetermined number of priorsamples. For example, an average impedance may be taken across the lastA impedance samples, where A may be equal to 10. Power, energy andvarious other values derivable from voltage, current and/or impedancemay also be calculated as stand-alone input variables or in differentpermutations. For example, total energy is used as an input variable insome forms. Total energy may indicate a sum of energy delivered to theultrasonic system since activation. This may be derived, for example, bymultiplying a summation of power by time throughout the activation. Animpedance curve or shape indicates changes in impedance sinceactivation. In some forms, a spline fit or other smoothing function maybe applied to the impedance curve. Application of a smoothing functionmay accentuate inflection points, the presence or position of which maybe utilized as input variables. For example, the impedance curve, insome forms, may experience a sudden drop as cutting occurs. Variousexample input variables, such as the impedance curve, are described as acurve or array of values. Such variables may be input to the neuralnetwork 3150 or similar model in any suitable form including, forexample, by taking an area under the curve, taking one or more peakvalues, taking an average or running average of the curve, etc. In someforms, integrals, peaks, averages, etc. of various curves may bebounded, for example, to exclude transient effects from activation.Additional variables may include, for example, a total energy (e.g.,since activation), a total change in impedance (e.g., since activation),etc.

Various input variables are based on the resonant frequency of thesurgical system (e.g., transducer, waveguide and blade). The resonantfrequency of the surgical system may be manifested in the frequency ofthe drive signal. For example, as described herein, the generator may betuned to drive the surgical system (e.g., provide a drive signal) at thesystem's resonant system. In some forms, the resonant frequency itself(e.g., a current or instantaneous resonant frequency) may be an inputvariable. Resonant frequency may be sampled at any suitable intervalsuch as, for example, at the data cycle of the neural network or othermodel. Another example resonant frequency variable describes a change inthe resonant frequency over the course of tissue treatment. For example,the change in resonant frequency may be set equal to a differencebetween a current resonant frequency value and a frequency value at theactivation and/or at a set point after the activation (e.g., 0.5 secondsafter activation). Yet another resonant frequency variable describes afrequency derivative dF/dt, or an instantaneous slope of the resonantfrequency. An additional resonant frequency variable may be derived bytaking an average of frequency derivative values. One example averageincludes all frequency derivative values since activation and/orfrequency derivative values over a predetermined period such as, forexample, the past 10 data cycles of the neural network 3150. In someforms, multiple average frequency derivative variables may be used, witheach variable calculated over a different period (e.g., a differentnumber of past data cycles of the neural network 3150 or other model).Various different permutations of the resonant frequency variablesdescribed herein may also be used. One example resonant frequencyvariable describes a maximum average frequency derivative calculatedover a preceding A average dFdt values, where A may correspond to anumber of data cycles of the neural network 3150 or other model. Forexample, A may be equal to 10. Another example input variable is a phasemargin. The phase margin describes a difference in phase between thedrive signal and the displacement of the blade. The phase margin may bemeasured in any suitable manner for example, as described incommonly-owned U.S. Pat. No. 6,678,621, entitled “Output DisplacementControl Using Phase Margin In An Ultrasonic Hand Piece,” which isincorporated herein by reference in its entirety.

In various forms, the neural network 3150 or other model receives inputvariables having values that describe a specific surgical system (e.g.,system-specific variables). System-specific variables may describeproperties any component or group of components of a surgical systemincluding, for example, a hand piece, a blade, a waveguide, an endeffector, a clamp arm, a clamp pad, etc. In this way, system-specificvariables may serve to provide a “fingerprint” of each surgical system.Different system-specific variables may be measured and utilized invarious ways. For example, system-specific variables may be used in boththe training and execution of the neural network 3150 or other model.

Some system-specific variables describe properties of the surgicalsystem, or components thereof, that can be physically measured. Systemlength describes the length of the surgical system (e.g., the waveguideand blade thereof). Example system lengths include 23 cm, 36 cm and 45cm. In some forms, separate neural networks 3150 may be trained andutilized for systems having different lengths, however, this may beavoided by utilizing system length as an input variable.

Some system-specific input variables describe properties of theultrasonic blade. For example, an individual blade gain describes aratio of an increase or decrease in displacement from a transducer tothe tip of a blade (e.g., the blade gain may describe the combination ofa blade and a wave guide). The gain of any given ultrasonic blade may bedetermined by the physical properties of the blade itself including, forexample, discontinuities in the diameter of the blade. Different bladesmanufactured to the same specifications may have slightly differentblade gains, for example, due to manufacturing tolerances. For example,the gain for one suitable blade may be 3.5±0.2. In various forms, bladegain is measured during the manufacturing and/or testing of the surgicalsystem. For example, a laser vibrometer or other suitable instrument maybe utilized to measure the displacement of the blade when driven by agenerator and hand piece with known gains.

Another blade-specific variable is the natural resonant frequency of theblade. This may also be referred to as the quiescent resonant frequency.The natural resonance frequency is a function of the physical propertiesof the blade. In various forms, natural resonant frequency is measuredduring manufacturing or testing of a blade (or associated system), forexample utilizing an impulse excitation or ping test. According to aping test, sound waves or vibrations over a range of frequencies areprovided to the (usually unloaded) blade. The frequency at which theblade is caused to resonate is noted. For example, a microphone or otheraudio sensor may be used to record the response of the blade to pings ofvarious frequencies. The frequency content of the measured values may beanalyzed to identify resonance. Yet another blade-specific variable isthe Q factor for the blade. The Q factor describes the bandwidth of theblade relative to its center frequency. In other words, the Q factordescribes how tightly packed the frequency spectrum of the blade isaround the resonant frequency. Q factor may be measured, for example,utilizing commonly available spectrum analyzer equipment, for example,during manufacture or testing of a blade or associated system.

An additional blade-specific variable is the blade length. For example,due to manufacturing tolerances, not every blade of the same design willhave the same length. Exact blade lengths may be measured using anysuitable measurement technique or equipment including, for example,micrometers, optical systems, coordinate measurement machines, etc.Blade deflection describes the degree that the blade deflects when incontact with the clamp arm. The degree of blade deflection may bemeasured, for example, utilizing a non-contact laser displacementinstrument, a dial indicator, or any other suitable instrument. Variousacoustic properties of blades may also be utilized as blade-specificinput variables. A Poisson's ratio for different blades may be measuredutilizing strain gauges to measure transverse and axial strain and/ormay be derived from the blade material. The speed of sound in differentblades may also be measured and/or derived from blade materials. Otheracoustic properties that are potential input variables include the phasevelocity, density, compressibility or stiffness, bulk modulus, etc. Forexample, many acoustic properties of blades, clamp pads, etc. areprovided by the material manufacturers.

Additional blade-specific variables include a surface coefficient offriction and a projected sealing surface. The surface coefficient offriction may be relevant to models of tissue effect because thecoefficient of surface friction may relate to the power delivered totissue, for example, according to Equation (11) below:Power=μ×2π*d*f*N  (11)In Equation (11), μ is the coefficient of surface friction (e.g.,dynamic friction); f is the frequency of the drive signal (e.g., theresonant frequency of the system); N is the normal force; and d is thedisplacement of the blade. The coefficient of surface friction may bemeasured in any suitable manner. For example, the blade may be mountedto a turn table and rotated while a known normal force is applied. Insome forms, Equation (11) above also considers the projected sealingsurface, as indicated by Equation (12) below:Power density=(μ×2π*d*f*N)/SS  (12)In Equation (12), SS is the projected sealing surface. The projectedsealing surface may be estimated, for example, based on the geometricconfiguration of the blade. For example, the blade length, width andcurvature may be relevant. A related example input variable is bladeclock. For example, in some forms the blade is curved. A blade clockdescribes an angular direction of blade curvature about the longitudinalaxis.

In various forms, the way in which a surgical system acts on tissuedepends on the way that the clamp arm and blade engage the tissue. Thismay, in turn, depend on various system-specific dimensions otherproperties. For example, various system-specific variables describe theinterrelationship between the blade, the clamp arm and the clamp pad.One such example input variable is the clamping force provided betweenthe blade and the clamp arm. For example, the clamping force maycorrespond to F_(T), described herein above with respect to Equation(1). Clamping force may be measured in any suitable manner. For example,with reference to the surgical system 19 shown with respect to FIGS.1-3, the clamp arm 56 may be secured in an open position (e.g., not incontact with the blade 79). A force transducer may be secured to theclamp arm 56, for example, at a midpoint between the pivot point and thedistal-most end of the clamp arm 56. Then the handle 68 may be actuatedto close the clamp arm 56 against the blade 79. The force transducer maymeasure the force provided. In some forms, the trigger position may bemonitored to derive an input variable expressing the clamp force versustrigger position. In some forms, the maximum force is used. In someforms, clamping force is measured with the clamp arm secured in on-openpositions. For example, a pressure sensor, such as those available fromTEKSCAN, may be placed between the blade and clamp arm.

Similar variables include a trigger displacement, a trigger force, and atube sub-assembly spring force. The trigger displacement is the distancethat the trigger 34, 4120 (FIG. 93) is pivoted to close the clamp armagainst the blade. The displacement of the trigger may correspond todegree to which a spring is displaced to close the clamp arm. Forexample, a spring 5051 is shown in FIG. 105. Referring now to FIGS. 93,95 and 105, although the spring 5051 is not specifically illustrated inFIG. 95, it will be appreciated that the spring 5051 or a similarspring, may be coupled to the yoke 4174 of FIG. 95 and to the handle4122 in a manner similar to that shown in FIG. 105. As described withrespect to FIGS. 93 and 95, proximal motion of the trigger 4120 leads todistal motion of the yoke 4174 and reciprocating tubular actuatingmember 4138 to close the clamp arm 4150 and blade 4152. As the yoke 4174moves distally, it may expand the spring 5051. Accordingly, thedisplacement of the trigger (e.g., trigger 4120) indicates the expansionof the spring (e.g., 5051) and, therefore, may serve as a proxy forclamp force. Trigger force (e.g., the force required to be provided tothe trigger) may also be used as an input variable. Trigger displacementand force may be measured in any suitable manner. In some forms, a tubesub-assembly force may also be measured and used as an input variable.For example, referring again to FIG. 95, the tube sub-assembly forcerepresents the force provided to the clamp arm 4150 and blade 4152 bythe reciprocating actuating member 138. The various displacements andforces described herein may be measured in any suitable manner utilizingany suitable equipment including, for example, vision measurementsystems, strain gauges, dial indicators, etc.

Other suitable clamping-related variables relate to a pressure profile.The pressure profile describes a distribution of pressure along theblade and clamp arm when the clamp arm is closed. A clamping profile maybe measured in any suitable manner. For example, a pressure sensor, suchas a sensor available from TEKSCAN, may be placed between the blade andthe clamp arm. The clamp arm may then be closed (e.g., utilizing trigger34 and/or trigger 4120 described herein) and the resulting force (and/orforce distribution) is measured. In some forms, clamping forces may betaken over less than the entire length of the clamp arm. For example,clamping force at a particular position on the clamp arm or blade (e.g.,at a proximal portion of the clamp arm) may be utilized as an inputvariable to the neural network 3150 or other suitable model.

Various other clamping-related input variables comprise a clamp armdeflection, a clamp arm position or ride, a jaw angle at full opentrigger, and pad height. Clamp arm deflection is a measure of the degreeof deflection in the clamp arm when closed against the blade. A clamparm position or ride, also referred to as a jaw angle at full opentrigger, describes a distance or angle between the clamp arm and theblade. For example, the jaw angle at full open trigger may be measuredutilizing a vision system, an optical comparator, a protractor, etc. Apad height may describe a thickness of the clamp arm pad. These valuesmay be measured in any suitable manner. For example, a vision system maybe utilized to capture images of the blade and derive clamp armdeflections, etc. Also, various mechanical or optical range findingtechniques may be used to measure specific dimensions. Additionalclamping-related variables may describe properties of the pad (e.g.,clamp pad 58). Examples of such parameters may include, a pad lotnumber, dimensions of the pad, a material distribution of the pad, amaterial hardness of the pad, thermal properties of the pad, as well asaverage values for these or similar values over a production lot.

In some forms, system-specific variables are assigned values based onmeasurements made during test procedures. For example, some inputvariables are determined during a system burn-in. One form of a burn-inis described herein above, with respect to FIGS. 26-28. A burn-in may beperformed under known (and repeatable) conditions such as, for example,with the instrument in air, fully clamped, and dry (e.g., nothingbetween the clamp arm and blade). In some forms, a frequency slopeduring burn-in may serve as an input variable along with similar valuessuch as, for example, power, energy, voltage, a rate of power change(dPower/dt); a rate of energy change (dEnergy/dt); a rate of change involtage (dV/dt); a rate of change in current (dI/dt); a rate of changein frequency (df/dt); a rate of change in impedance (dZ/dt), peakimpedance, etc. In some forms, when the burn-in is performed in air(e.g., with the blade against the pad), the variables described abovemay remain relatively constant throughout the burn-in. If the variableschange, however, the frequency slope or other variable may be taken at apredetermined time after actuation, averaged or otherwise mathematicallycombined over all or portion of the burn-in cycle, etc.

In some forms, a frequency slope or other value is taken under burn-inconditions with the generator power set across different power levels.For example, a frequency slope or other measurement may be taken withthe generator set at a first power and a second frequency slope or othermeasurement may be taken with the generator set at a second power level.In some forms, the burn-in may be performed with a tissue (e.g., porcinetissue) or a tissue surrogate (sponge material, etc.) positioned betweenthe clamp arm and the blade. In some forms, the frequency slope andrelated variables may change as the tissue surrogate is transected. Forexample, the frequency slope may be taken at various different points inthe burn-in cycle, averaged over all or a portion of the burn-in cycle,etc. Another test-related variable is the number of burn-in cycles thatare performed. For example, in some forms, multiple burn-in cycles maybe performed, for example, if there is a problem with the instrument orwith the test procedure at the first burn-in.

After performing a burn-in, various other characteristics of thesurgical system may be measured (and used as input variables). Forexample, the burn-in may create an indentation on the clamp padcorresponding to the blade. Analysis of the indentation may yield aburn-in depth (e.g., the depth of the indentation). The depth may bemeasured with any suitable device. In some forms, the burn-in depth maybe measured with a vision system, laser range finder and/or othermechanical or optical measurement tool. In some forms, the burn-in depthis taken at various points on the clamp pad to indicate a burn-in depthdistribution (e.g., a contact profile). Also, in some forms, a point ofclamp arm contact may also be derived from the indentation. For example,the deepest portion of the indentation may correspond to the point offirst contact.

Still other system-specific input variables are measured in a freestate. A free state may be recreated with the clamp not in contact withthe blade, and the blade running in air. Variables measured in a freestate may include power consumption, device impedance, frequency slopesacross different power levels, blade impedance at different powerlevels, current, voltage and impedance of the hand piece, etc. Invarious forms, system and environment-related variables may be measuredduring a pre-run. For example, various surgical systems are configuredto require a pre-run test prior to operation on tissue. This may serve,for example, to ensure that the surgical system has been properlyassembled. During the pre-run test, however, various system-specificvariable values may be captured including, for example, voltage,current, impedance, resonant frequency and permutations thereof, forexample, as described herein.

Additional system-specific variables relate to the temperature responseof the blade and/or clamp arm. For example, a clamp arm temperatureresponse describes the way that a particular clamp arm heats whenexposed to a heat influx. The temperature of a clamp arm may bemeasured, for example, with an infrared thermometer. A clamp armtemperature response may be expressed as a number of degrees of heatingin temperature per watt of heat influx. Similarly, a clamp armtemperature cooling curve may be a measure of how a given blade cools inroom temperature air per unit time, for example, expressed in degreesper unit time. Similar input variables may be based on the bladeincluding, for example, a blade temperature response and a blade coolingcurve. Another example temperature response variable comprises a bladeimpedance versus temperature. This may be a measure of an acousticimpedance of the blade (e.g., as expressed by an electrical impedance ofthe transducer) as a function of temperature. Since a change in bladetemperature may cause a change in frequency, the components securing theblade and waveguide within the shaft may not be necessary be at exactnodal points (e.g., positions on the waveguide with zero transversedisplacement). Accordingly, when the components are not at the exactnodal points, they may cause acoustic impedance in the system when inair. Measuring how this changes and resulting changes in frequency maymake it possible to model not only blade temperature, but also how farback on the blade (e.g., toward the handle) the blade temperature haschanged. The respective temperature responses and/or cooling curves maybe used as inputs to the neural network 3150 in any suitable manner. Forexample, the slope of the respective curves, a knee value where theslope changes, or any other suitable value may be selected.

Other example, system-specific variables comprise the age of theproduction line on which a system was produced and a transversefrequency measured within the blade, for example, at a burn-in. Forexample, production machinery may change over its lifetime, causingblades and other components produced at different point in theproduction machinery lifecycle to behave differently. Transversefrequencies describe vibrations in the blade that are in a directionorthogonal to that of the shaft and may be measured, for example,utilizing a vector signal analyzer or spectrum analyzer, such as theN9030A PXA Signal Analyzer available from AGILENT TECHNOLOGIES.Transverse frequencies may be measured in any suitable conditionsincluding, for example, in a predetermined condition set such as aburn-in or free state.

Various input variables for the neural network 3150 may be based on thehand piece or transducer used by the surgical system to treat tissue.Examples of such variables may include an impedance of the transducer,as described above, a resonant frequency of the hand piece, a currentset point of the hand piece, etc. The resonant frequency of a hand piecedescribes the resonant frequency of the hand piece independent of thewaveguide or blade. For example, the resonant frequency of the handpiece may be measured at the time of manufacture. The current set pointfor a hand piece describes a level of current that is to be provided toa particular hand piece to provide a predetermined displacement. Forexample, different hand pieces may have different current set pointsbased on different manufacturing tolerances. The current set point,resonant frequency, and other variable values describing a hand piecemay be stored, for example, at an electrically erasable programmableread only memory (EEPROM) or other storage device associated with thehand piece. For example, the generator may interrogate the hand piece toretrieve hand piece-specific variables. In some forms, utilizing handpiece-specific variables may provide additional clarity to various othersystem-specific variables measured during manufacturing and/or testing.For example, when the system is utilized by a clinician, a different andoften newer hand piece may be utilized. Hand piece specific variablesmay correct for this.

It will be appreciated that the neural network 3150 may utilize any ofthe input variables described herein above. In some forms, the neuralnetwork 3150 may be evaluated utilizing matrix algebra. For example,four matrices maybe used. A 1×I input matrix (O_i) may include (e.g.,scaled) values for the I input neurons. An I×J hidden neuron omegamatrix (W_ij) comprises omega (ω) values used to calculate values ofhidden neurons 3154. A J×K output neuron omega matrix (W_jk) comprisesomega (ω) values used to calculate the values of output neuron orneurons 3156. A 1×J hidden neuron constant matrix (O_j) comprisesconstant θ values for the hidden neurons 3154. A 1×K output neuronconstant matrix (O_k) comprises constant θ values for the outputneuron(s) 3156. For any given cycle, the output of the neural networkmay be calculated by evaluating the matrices as indicated by Equations(13)-(16) below:x_j=O_i*W_ij+O_j  (13)The result of Equation (13), x_j, may be the weighted sums of the inputneuron values for each hidden neuron 3154. Matrix x_j may be processedelement-by-element through an equation, such as Equation (14) below,resulting in a matrix of equal size, O_j.O_j=(1+exp(−x_j))·{circumflex over ( )}(−1*Z)  (14)The result of Equation (14), O_j may be the values for each of thehidden neurons 3154. In Equation (12), Z corresponds to an matrix ofones having a size K×J.x_k=O_j*W_jk+O_k  (15)The result of Equation (15), x_k, may be the weighted sums of the hiddenneuron values for each output neuron 3156. Matrix x_k is processedelement-by-element through an equation, e.g., Equation (16), resultingin a matrix of equal size, O_k.O_k=(1+exp(−x_k)){circumflex over ( )}(−1*Z1)  (16)The result of Equation (16), O_k, may be the output of the neuralnetwork. In Equation (15), Z1 may be a matrix of ones having a size K×1.

The neural network may be trained in any suitable manner. For example,in some forms, the neural network may be trained utilizingback-propagation. During back-propagation training, the data flow of theneural network is reversed. For example, values for error versus actualoutput are used to modify individual weight and constant parameters.FIG. 87 is a logic flow diagram of one form of an algorithm for traininga neural network, such as the neural network 3150, utilizingback-propagation. At 3172, relevant data sets may be generated. In someforms, separate data sets are generated for training and testing toensure that actual pattern recognition is taking place instead of thenetwork merely learning the data files being used for training. Eachdata set may comprise, for example, all of the necessary inputs (forexample, see TABLE 8). Each data set may also comprise actual valuesdescribing the state of the instrument and/or tissue corresponding toeach set of input values, which represent the value modeled by theneural network. For example, in some forms, the actual values maycomprise transection data, which may indicate whether the tissue hasreached a threshold level of transaction (e.g., 80% transaction) uponany given set of input values. Neural networks trained in this mannermay provide an output indicating tissue has or has not reached thethreshold level of transection. It will be appreciated that any suitablevalue may be used including, for example, any other suitable level oftransection, complete transection, tissue sealing, etc. Whether anygiven sample has reached 80% or any other suitable threshold transactionstate may be determined, in some forms, based on the amount tissue alongthe length of the cut that is transected. For example, transection maynot occur all at once and, instead, may occur from front-to-back,back-to-from or middle out. Whether any given tissue sample is,transected to the threshold value may be determined according to anysuitable method. For example, in some forms, a video camera may record acut and a user may visually determine whether a transection is completeto the threshold value. Also, in some embodiments, an optical (e.g.,laser) positioning sensor may be utilized to measure a position of theclamp arm relative to the blade. The inclination of the clamp armrelative to the blade may indicate the degree of transection.

At 3174, the neural network may be created. For example, the values forthe weights and constants of the various neurons 3154, 3156 mayberandomly initialized (e.g., utilizing the MATLAB “rand” function, whichgenerates a uniform distribution). In some forms, a value range of −2.5to 2.5 may be utilized as these values tend to result in outputs in therange of 0-1 when processed by a sigmoid activation function. At 3176,the network 3150 may be run forward on the input data to generate apredicted output (or outputs if there are multiple output nodes). At3178, an error may be calculated. The error is a difference between thepredicted output from 3176 and the actual value of the tissue orinstrument property, as described herein. In various forms, the outputor outputs may be denoted as binary numbers where one (1) corresponds tothe existence or truth of the condition and zero (0) corresponds to thenon-existence or falsity of the condition. For example, when thecondition is 80% transection, the output should be 1 when the tissue is80% transected and 0 when the tissue is not (yet) 80% transected. Insome forms, the condition may be considered true when the output of theneural network 3150 exceeds a threshold value (e.g., 0.85).

At 3180, the weights for each node are evaluated. For example, for eachweight a partial derivative is found of the output or error (E) withrespect to the weight (omega (ω)). This may be represented as δE/δω_(ij) for connections between the input layer 3152 and the hidden layer3154 and as δE/δ ω_(jk) for connections between the hidden layer 3154and the output layer 3156. At 3182, the constants for each node areevaluated. For example, for each constant, a partial derivative is foundof the output or error (E) with respect to the constant θ. This may berepresented as δE/δ θ_(i) for connections between the input layer 3152and the hidden layer 3154 and to δE/δ θ_(j) for connections between thehidden layer 3154 and output layer 3156. At 3184, deltas may becalculated for each weight and constant. The deltas may found bymultiplying each partial derivative by a gradient constant, η. In someforms, a value of 0.1 may be used for η. The deltas may then be added tothe original values of each weight and constant. Actions 3176, 3178,3180, 3182, and 3184 may be repeated for subsequent cycles of the inputdata. In some form, the network 3150, once trained, may be tested. Forexample, the network 3150 may be tested, as described herein, on atesting data set distinct from the training data set. In various forms,a neural network or other multi-variable model may be pre-trained.Resulting model parameters (e.g., network configuration, values forweights and constants, etc.) may be determined and stored at a generatorand/or instrument. The values may be utilized to execute the modelduring use.

FIG. 88 is a logic flow diagram of one form of an algorithm 3160 fordetecting a condition set for an ultrasonic instrument utilizing amulti-variable model, such as the neural network 3150 described herein.As with the other instrument control algorithms described herein, thealgorithm 3160 is described as being executed by a generator, such asgenerators 30, 50, 1002 described herein, but in some forms may beexecuted by an instrument itself. Also, although a neural network isdescribed herein, it will be appreciated that the algorithm 3160 may beexecuted utilizing any suitable type of model including, for example,genetic algorithm models, classification tree algorithm models,recursive Bayesian models, etc. At 3162, the generator may execute themulti-variable model. Executing the multi-variable model may compriseproviding input values to the model, processing the input values, andgenerating an output. For example, a process for executing an exampleneural network is described herein above in conjunction with Equations(11)-(14). At 3164, the generator may determine whether the modeledcondition set is met. In the example above, this may involve determiningwhether 80% transection has been achieved (e.g., whether the value ofthe output node 3156 has exceeded a threshold value. If not, the modelmay continue to execute at 3162. If so, the trigger response associatedwith the condition set may be triggered at 3166. The response set mayinclude any suitable actions including, for example, providing feedbackindicating the truth of the condition set, modifying a drive signal forthe instrument, etc.

Although a neural networks, such as the network 3150 are describedherein, it will be appreciated that any other suitable type ofmulti-variable model may be utilized in addition to or instead of aneural network including, for example, genetic algorithm models,classification tree algorithm models, recursive Bayesian models, etc.For example, a recursive Bayesian model models the probability of anoutput event occurring (e.g., a threshold transection state), where theprobably is equal to zero at the beginning of the transection (e.g.,t=0) and continually increases with each time step. The amount ofincrease in the probability is based on whether certain criteria aremet. The criteria may represent threshold values of different inputvariables. For example, if “frequency slope<threshold 1” is true, it mayincrease the probability by a certain amount for each time step at whichit is true. If “frequency delta<threshold 2” is true, it could increasethe probability by an additional amount, where the sum of increases dueto different criteria at each time step indicates the increase inprobability at the time. When the probability reaches a threshold value(e.g., 0.85), the recursive Bayesian model may indicate that the modeledcondition is true.

Another type of suitable multi-variable model is a classification ordecision tree. A classification or decision tree comprises a pluralityof binary decisions arranged according to a hierarchy tree structure Forexample, in some embodiments, the generator may first determine if afrequency slope characterizing a drive signal provided to a surgicalinstrument is less than a threshold If not, then the change in frequencymay be measured against a second threshold. If the change in frequencyis less than the threshold, then the generator may provide feedbackindicating the end of the transection. If the change in frequency isgreater than the threshold, then the generator may not provide feedback.Referring back to the initial decision, if the frequency slop is lessthan the first threshold, then the generator may determine if a requiredtime before trigger is greater than a threshold. The required timebefore trigger may refer to a threshold amount of time after thefrequency slope is met before the generator provides feedback indicatingthe end of the transection. For example, this may correct for bouncinessin the frequency slope signal. If the required time before trigger haspassed, then the generator provides feedback indicating the end of thetransection. If not, then no feedback is provided.

FIG. 89 is a logic flow diagram showing one form of an algorithm 3570utilizing a multi-variable model such as, for example, the neuralnetwork 3150 or other model described herein. The algorithm 3570 isdescribed as being executed by a generator, such as generators 30, 50,1002 described herein, but in some forms may be executed by aninstrument itself. The algorithm 3570 comprises two action threads 3571,3573 which may execute concurrently. For example, a control thread 3571may comprise actions for controlling the ultrasonic surgical instrument.In this way, the control thread 3571 may be similar to the algorithms3021, 3021′, 3021″, 3100, 3120, described herein. A condition thread3573 may be similar to the condition monitoring algorithms describedherein with respect to FIGS. 15A-15C, FIGS. 20-22, FIGS. 57-60, etc.

Referring first to thread 3571, that control thread may be similar tothe algorithm 3021″ of FIG. 77. For example, at 3572, the generator mayreceive an activation request, similar to the activation request at 3020described herein above. At 3574, the generator may drive the endeffector at a first power level for a first period, for example, byproviding a first drive signal at the first power level. At 3576, afterthe expiration of the first period, the generator may drive the endeffector at a second power level for a second period, wherein the secondpower level is less than the first power level. This may beaccomplished, for example, by providing a second drive signal at thesecond power level. At the expiration of the second period, at 3578, thegenerator may drive the end effector at a third level for a third periodat a third power, for example, by providing a third drive signal at thethird power level. The third power level may be greater than the secondpower level and less than the first drive level or, in some forms, maybe equal to the first power level. At 3580, the generator may drive theend effector at a thermal management level, either at the expiration ofthe third period or as indicated by the condition thread 3573 asdescribed herein. According to the thermal management level or stage,the generator may reduce the power provided to the end effector so as toslow down the rate of excess heat production. For example, in one formentering the thermal management stage may entail reducing the power to alevel that is 75% of the first power level. Also, in some forms, thethermal management level or stage may entail ramping and/or steppingdown the power provided to the end effector.

Referring now to the condition thread 3573, the generator may, at 3582,execute a multivariable model, such as the neural network 3150 describedherein or any other multivariable model. At 3584, the generator maydetermine whether an output of the model meets a predeterminedthreshold. The threshold may indicate the truth or presence of one ormore of the conditions of the modeled condition set. If not, then thegenerator may continue to execute the model at 3582. If yes, thegenerator may wait an alert time period at 3586. At an expiration of thealert time period, the generator may generate feedback (e.g., audible,visual or tactile feedback) at 3588. The feedback may indicate the truthor presence of the detected condition. At 3590, the generator may wait athermal management time period. While waiting, the feedback initiated at3588 may be maintained. At 3592, the generator may determine whetherboth the first and second time periods (see thread 3571) have expired.If so, the generator may modify the power provided to the end effectorat 3596. If not, then, in some forms, the generator may wait until thefirst and second time periods expire, at 3594, before modifying thepower provided to the end effector at 3596. For example, the generatormay enter the thermal management level or stage.

FIG. 90 is a chart illustrating a drive signal pattern 3200 of oneimplementation of the algorithm 3170. In the example of FIG. 90, thefirst period is a time period of one second, the second period is a timeperiod of sixteen seconds. The first power level is 100% of the poweravailable from the generator (e.g., 100% of the power available at level5 provided by the GEN 11 generator available from Ethicon Endo-Surgery,Inc. of Cincinnati, Ohio). The second power level may be 50% of thepower available from the generator. The third power level may be 100% ofthe power available from the generator.

As illustrated, upon activation the end effector may be driven at thefirst power level, as indicated by 3572 (FIG. 89). The end effector isthen driven at the second power level for the second period, and drivenat the third power level at the expiration of the second period. Themulti-variable model may return a value indicating the truth of at leastone condition of the condition set at the point labeled “thresholdexceeded” (see 3584 of FIG. 89). T4, as shown in FIG. 90, may correspondto the alert time period. At the expiration of the alert time period,the generator may provide the feedback descried above with respect to3588 of FIG. 89. T5, as shown, may correspond to the thermal managementtime period. At its expiration, because the first and second time periodis expired (3194), the generator may modify the end effector drive level(3196) as shown by the point labeled “thermal management activated.” Forexample, the generator may provide a drive signal at a power level thatis lower than or equal to the first power level and greater than thesecond power level (e.g., 75% of the power available from thegenerator).

FIG. 91 is a chart illustrating a drive signal pattern 3202 of anotherimplementation of the algorithm 3570. In the example of FIG. 91, thetime periods and power levels are the same as illustrated with respectto FIG. 90. Upon activation, the end effector may be driven at the firstpower, as indicated by 3572. At the expiration of the first period, theend effector is driven at the second power level for the second period.In FIG. 91, however, the multi-variable model returns a value indicatethe truth of at least one condition of the condition set at the pointlabeled threshold exceeded before the expiration of the second timeperiod, at the point labeled “threshold exceeded.” As indicated at FIG.89, the generator may wait the alert time period and then initiate thefeedback of 3588 at the point labeled “feedback.” At the expiration ofthe thermal management time period (3190), the second period is stillnot expired. Accordingly, the generator waits until the end of thesecond period (3194) and then modifies the end effector drive level, forexample, by implementing the example thermal management level of 75% ofthe power available from the generator.

FIG. 92 is a logic flow diagram showing one form of an algorithm 3210for utilizing a multi-variable model to monitor a condition setcomprising multiple conditions. The algorithm 3210 is described as beingexecuted by a generator, such as one of the generators 30, 50, 1002described herein, but in some forms may be executed by an instrumentitself. In the example form shown in FIG. 92, the condition setmonitored by the multi-variable model comprises two conditions, acondition indicating the presence or absence of tissue seal and acondition indicating the presence or absence of tissue transection. Thetissue transection may be complete tissue transection and/or partialtransection (e.g., 80% transection, as described herein). At 3212 and3214, the generator may monitor model values indicating the truth orfalsity of the tissue seal and tissue transection conditions. In someforms, both the tissue seal and tissue transection conditions may bemonitored by the same model. For example, the neural network 3150described herein may be generated and trained with two output nodes3156. Also, in some forms, the generator implements separate models,with distinct models for each condition.

If the transection condition is met at 3216, it may indicate thattransection has occurred, or is set to occur, before sealing. As thismay be an undesirable occurrence, the generator may deactivate thesurgical instrument at 3528 to prevent transection from occurring beforesealing. At 3222, the generator may wait a first period. Waiting thefirst period, for example, may allow the tissue to complete sealingeither before transection occurs and/or before the clinician is providedwith an indication to open the end effector to release the tissue. Thefirst period may be a predetermined time period or, in various forms,may be based on the seal condition output of the model. At theexpiration of the first period, the generator may provide feedbackindicating the end of the seal and transect operation at 3224.Alternatively, after the expiration of the first period, the generatormay apply an amount of energy for a second period and then subsequentlydeactivate the instrument and provide feedback indicating the end of theseal and transect operation. If the transection condition is not met at3216, it may indicate that transection is not set to occur beforesealing. The generator may then determine at 3220 whether the sealcondition is true. If not, the generator may return to the monitoringactions 3212, 3210. If the seal condition is set to occur, the generatormay generate the feedback at 3224. In some forms, if the instrument isstill activated at 3224, the generator may deactivate the instrumentand/or deactivate the instrument after a delay period.

Various algorithms herein are described herein as being executed by agenerator. It will be appreciated, however, that in certain exampleforms, all or a part of these algorithms may be performed by internallogic 2009 of a surgical instrument (FIG. 16A). Also, various algorithmsdescribed herein above utilize various thresholds and flags such as, forexample, a threshold impedance, a time above impedance period, abaseline deviation threshold parameter frequency, a time above frequencydelta period, a load monitoring flag, a maintain status flag, etc. Suchthresholds, flags, etc., may be stored at any suitable locationincluding, for example, a generator and/or at an EEPROM or other storagedevice included with the surgical instrument.

Multi-function capabilities of many ultrasonic surgical instruments,challenge the ability of a user to comfortably access and operate themultiple functions and controls of the instrument. This includes, forexample, the ability to comfortably actuate the jaws of a clampingmechanism and activate hand control buttons/switches, sometimessimultaneously. As such, various user interface controls may bedesirable. One user interface design to control functions of theultrasonic surgical instrument may include a rotation mechanism betweentwo portions of the device requiring a rotatable electrical connection.Rotatable electrical connections may fail over time, requiring costlyrepairs or replacement of associated instrument components that mayotherwise have valuable operation life remaining. Accordingly, there isa need to extend the operational life of various ultrasonic surgicalinstruments by providing alternate solutions to costly repairs andpremature component replacements.

Ultrasonic surgical instruments, including both hollow core and solidcore instruments, are used for the safe and effective treatment of manymedical conditions. Ultrasonic surgical instruments, and particularlysolid core ultrasonic surgical instruments, are advantageous becausethey may be used to cut and/or coagulate tissue using energy in the formof mechanical vibrations transmitted to a surgical end effector atultrasonic frequencies. Ultrasonic vibrations, when transmitted totissue at suitable energy levels and using a suitable end effector, maybe used to cut, dissect, coagulate, elevate or separate tissue.Ultrasonic surgical instruments utilizing solid core technology areparticularly advantageous because of the amount of ultrasonic energythat may be transmitted from the ultrasonic transducer, through anultrasonic transmission waveguide, to the surgical end effector. Suchinstruments may be used for open procedures or minimally invasiveprocedures, such as endoscopic or laparoscopic procedures, where the endeffector is passed through a trocar to reach the surgical site.

Activating or exciting the end effector (e.g., cutting blade, ballcoagulator) of such instruments at ultrasonic frequencies induceslongitudinal vibratory movement that generates localized heat withinadjacent tissue, facilitating both cutting and coagulating. Because ofthe nature of ultrasonic surgical instruments, a particularultrasonically actuated end effector may be designed to perform numerousfunctions, including, for example, cutting and coagulating.

Ultrasonic vibration is induced in the surgical end effector byelectrically exciting a transducer, for example. The transducer may beconstructed of one or more piezoelectric or magnetostrictive elements inthe instrument hand piece. Vibrations generated by the transducersection are transmitted to the surgical end effector via an ultrasonicwaveguide extending from the transducer section to the surgical endeffector. The waveguides and end effectors are designed to resonate atthe same frequency as the transducer. When an end effector is attachedto a transducer the overall system frequency may be the same frequencyas the transducer itself. The transducer and the end effector may bedesigned to resonate at two different frequencies and when joined orcoupled may resonate at a third frequency. In some forms, thezero-to-peak amplitude of the longitudinal ultrasonic vibration at thetip, d, of the end effector behave as a simple sinusoid at the resonantfrequency as given by:d=A sin(ωt)  (17)where: ω=the radian frequency which equals 2π times the cyclicfrequency, f; and A=the zero-to-peak amplitude. The longitudinalexcursion is described by a as the peak-to-peak (p-t-p) amplitude, whichmay be twice the amplitude of the sine wave or 2 A.

Various forms of ultrasonic surgical instruments described hereincomprise a first structure and a second structure where the secondstructure is rotatable relative to the first structure. In some forms,electrical communication between the first structure and the secondstructure may be provided through a rotatable electrical connection. Inone form, the first structure comprises an ultrasonic hand piececomprising an ultrasonic transducer, which in many designs, may be usedto rotate a shaft extending distally from the hand piece. Rotation ofthe hand piece may include rotation relative to a second structure, suchas a handle assembly or another component of the instrument in whichelectrical coupling is required. For example, in one form, the secondstructure may comprise a user interface. According to one form, the userinterface may be engaged by the user to provide operation instructionsor signals between the hand piece, power generator, or another componentof the ultrasonic surgical system. In one form, instructions or signalsprovided at the user interface may be electrically coupled through therotatable electrical connection to provide signals that may be used tocontrol or provide information related to an operation associated withthe ultrasonic surgical instrument. In one form, the user interface maycomprise buttons, switches, knobs, or other various interfaces known inthe art. In one form, the rotatable electrical connection mayelectrically couple an end effector that is rotatable relative toanother component of the instrument, such as a hand piece or handleassembly, to provide electrical communication therebetween.

FIGS. 93-94 illustrate one form of an ultrasonic surgical instrument4100. The ultrasonic surgical instrument 4100 may be employed in varioussurgical procedures including endoscopic or traditional open surgicalprocedures. In one form, the ultrasonic surgical instrument 4100comprises a handle assembly 4102, an elongated endoscopic shaft assembly4110, and an ultrasonic hand piece 4114 comprising an ultrasonictransducer assembly. The handle assembly 4102 comprises a triggerassembly 4104, a distal rotation assembly 4106, and a switch assembly4108. The ultrasonic hand piece 4114 is electrically coupled to agenerator 4116 via a cable 4118. The elongated endoscopic shaft assembly4110 comprises an end effector assembly 4112, which comprises elementsto dissect tissue or mutually grasp, cut, and coagulate vessels and/ortissue, and actuating elements to actuate the end effector assembly4112. Although FIGS. 93-94 depict an end effector assembly 4112 for usein connection with endoscopic surgical procedures, the ultrasonicsurgical instrument 4100 may be employed in more traditional opensurgical procedures. For the purposes herein, the ultrasonic surgicalinstrument 4100 is described in terms of an endoscopic instrument;however, it is contemplated that an open version of the ultrasonicsurgical instrument 4100 also may include the same or similar operatingcomponents and features as described herein. Additional embodiments ofsimilar ultrasonic surgical instruments are disclosed in commonly-ownedU.S. Patent Application Publication No. 2009-0105750, which isincorporated herein by reference in its entirety.

The ultrasonic transducer of the ultrasonic hand piece 4114 converts anelectrical signal from a power source, such as the ultrasonic signalgenerator 4116 or battery (not shown), into mechanical energy thatresults in primarily a standing acoustic wave of longitudinal vibratorymotion of the transducer and the blade 4152 portion of the end effectorassembly 4112 at ultrasonic frequencies. As shown in FIG. 94, the handleassembly 4102 is adapted to receive the ultrasonic hand piece 4114 atthe proximal end through a proximal opening 4156. In one form, in orderfor the ultrasonic hand piece to deliver energy to the end effectorassembly 4112, which may include a clamp arm 4150 movably opposed to ablade 4152, components of the hand piece 4114 must be acousticallycoupled to the blade 4152. In one form, for example, the ultrasonic handpiece 4114 comprises a longitudinally projecting attachment postcomprising a waveguide coupling, which is illustrated as a threaded stud4133 in FIG. 94, at a distal end of the hand piece 4114 for acousticallycoupling the ultrasonic hand piece 4114 to the waveguide 4128 (see FIG.95). The ultrasonic hand piece 4114 may mechanically engage theelongated endoscopic shaft assembly 4110 and portions of the endeffector assembly 4112. For example, referring to FIG. 94, in one form,the ultrasonic transmission waveguide 4128 comprises a longitudinallyextending attachment post 4129 at a proximal end 4131 of the waveguide4128 to couple to the surface 4166 of the ultrasonic hand piece 4114 bya threaded connection, such as the stud 4133. That is, the ultrasonictransmission waveguide 4128 and the ultrasonic hand piece 4114 maymechanically couple via a threaded connection therebetween to threadablyengage and acoustically couple the ultrasonic transmission waveguide4128 and the ultrasonic hand piece 4114. In one form, when theultrasonic hand piece 4114 is inserted through the proximal opening4156, the ultrasonic hand piece 4114 may be secured to the waveguide4128 with a torque wrench. In other forms, the distal waveguide couplingmay be snapped onto the proximal end of the ultrasonic transmissionwaveguide 4128. The ultrasonic hand piece 4114 also comprises a distalrim portion 4158 with a circumferential ridge 4160 configured to engagethe handle 4102 through the proximal opening 4156. As described in moredetail below, the distal rim portion 4158 may comprise one or moreelectrical contacts configured to electrically couple to the handleassembly 4102, for example, to receive electrical control operationinstructions from the user via the handle assembly 4102.

In one form, the handle assembly 4102 comprises a trigger 4120 and afixed handle 4122. The fixed handle 4122 may be integrally associatedwith the handle assembly 4102 and the trigger 4120 may be movablerelative to the fixed handle 4122. The trigger 4120 is movable indirection 4121 a toward the fixed handle 4122 when the user applies asqueezing force against the trigger 4120. The trigger 4120 may be biasedin the direction 4121 b such that the trigger 4120 is caused to move indirection 4121 b when the user releases the squeezing force against thetrigger 4120. The example trigger 4120 also includes a trigger hook 4124extension to provide an additional interface portion from which thetrigger 4120 may be operated.

FIG. 95 shows a cross-section of the handle assembly according tovarious forms. The handle assembly 4102 comprises a trigger 4120 movablein directions 4121 a and 4121 b with respect to a fixed trigger 4122.The trigger 4120 is coupled to a linkage mechanism to translate therotational motion of the trigger 4120 in directions 4121 a and 4121 b tothe linear motion of a reciprocating tubular actuating member 4138 inalong the longitudinal axis “T”. The trigger 4120 comprises a first setof flanges 4182 with openings formed therein to receive a first yoke pin4176 a. The first yoke pin 4176 a is also located through a set ofopenings formed at the distal end of the yoke 4174. The trigger 4120also comprises a second set of flanges 4180 to receive a first end 4176a of a link 4176. As the trigger 4120 is pivotally rotated, the yoke4174 translates horizontally along longitudinal axis “T”. Thus,referring to FIG. 93, when the trigger 4120 is squeezed in direction4121 a the reciprocating tubular actuating member 4138 moves indirection 4146 a to close the jaw elements comprising the clamp arm 4150and blade 4152 of the end effector assembly 4112. When released, thetrigger 4120 may be biased to move in direction 4121B when the squeezingforce is released. Accordingly, the yoke 4174 and the reciprocatingtubular actuating member 4138 move in direction 4146 b to open the jawsof the end effector assembly 4112. In some embodiments a spring 5051(FIG. 105) is coupled between the yoke 4174 and the handle assembly4102. The spring 5051 biases the trigger 4120 to the open position shownin FIG. 95.

Further to the above, the distal rotation assembly 4106 may be locatedat a distal end of the handle assembly 4102 when the ultrasonic handpiece 4114 is received for and mechanically and acoustically coupled tothe handle assembly 4102. In one form, the distal rotation assembly 4106comprises a ring or collar shaped knob 4134. The distal rotation knob4134 is configured to mechanically or frictionally engaged with theultrasonic hand piece 4114. As previously discussed, the ultrasonic handpiece 4114 is mechanically engaged to the elongated endoscopic shaftassembly 4110. Thus, rotating the rotation knob 4134 rotates theultrasonic hand piece 4114 and the elongated endoscopic shaft assembly4110 in the same direction 4170.

In various forms, the ultrasonic surgical instrument 4100 may compriseon or more user interfaces to provide electrical control instructions tocontrol the operation of the instrument 4100. For example, in one form,a user may employ a footswitch 4111 to activate power delivery to theultrasonic hand piece 4114. In some forms, the ultrasonic surgicalinstrument 4100 comprises one or more electrical power setting switchesto activate the ultrasonic hand piece 4114 and/or to set one or morepower settings for the ultrasonic hand piece 4114. FIGS. 93-95illustrate handle assemblies 4102 comprising a switch assembly 4108. Theswitch assembly 4108 may comprise a user interface associated with atoggle or rocker switch 4132 a, 4132 b, for example. In one form, theswitch assembly 4108 may be at least partially associated with thehandle assembly 4102 and may be implemented as a MIN/MAX rocker-style or“toggle” switch. In one position, the MIN/MAX rocker-style switch (or“toggle” style) buttons 4132 a, 4132 b may create an easily accessiblelocation for power activation. For example, the user also may operate afirst projecting knob 4132 a to set the power to a first level (e.g.,MAX) and may operate the second projecting knob 4132 b to set the powerto a second level (e.g., MIN). The toggle switch 4132 a, 4132 b may becoupled to the generator 4116 to control the operation of theinstrument, such as activation or power delivery to the ultrasonic handpiece 4114. Accordingly, in various forms, the toggle switch 4132 a,4132 b and the generator 4116 may be electrically coupled through arotatable connection. For example, in certain forms, the surgicalinstrument 4100 may comprise a rotatable electrical connection allowingthe electrical power control operations provided at the handle assembly4102 to electrically communicate with the generator 4116 via theultrasonic hand piece 4114. The toggle switch 4132 a, 4132 b maycomprise a control selector and/or an activation switch electricallycoupled to a circuit board, e.g., a printed circuit board, flex circuit,rigid-flex circuit, or other suitable configuration. In one form, theswitch assembly 4108 comprises a toggle switch having a first electricalcontact portion 4132 a and a second electrical contact portion 4132 bconfigured for modulating the power setting of the ultrasonic hand piece4114 between a minimum power level (e.g., MIN) and maximum power level(e.g., MAX). The toggle switch may be electrically coupled to a handleportion of a circuit, which may include, for example, a flex circuitconfigured to electrically couple to the generator 4116 via a rotatableconnection through the hand piece 4114 to control the activation of theultrasonic hand piece 4114. In various forms, the switch assembly 4108comprises one or more electrical power setting switches to activate theultrasonic hand piece 4114 to set one or more power settings for theultrasonic hand piece 4114.

As those having skill in the art will appreciate, a generator 4116 mayprovide activation power to the ultrasonic hand piece 4114 via cable4118, for example. As described above, the handle assembly 4102 may beconveniently used to provide electrical power control instructions tothe generator 4116 to control power delivery to the ultrasonic handpiece 4114, for example, through one or more switches associated withthe switch assembly 4108. For example, in operation, the one or moreswitches 4108 may be configured for electrical communication with thegenerator 4116 to control electrical power delivery and/or electricalpower operation features of the ultrasonic surgical instrument 4100. Itis to be appreciated that in at least one form, the generator 4116 maybe internal to the hand piece 4114.

As introduced above, the ultrasonic hand piece 4114 may be configured torotate relative to the handle assembly 4102 or component thereof via thedistal rotation knob 4134, to rotate the ultrasonic transmissionwaveguide 4128 and locate the end effector assembly 4112 in the properorientation during a surgical procedure. Accordingly, in various forms,the ultrasonic hand piece 4114 may be electrically coupled at one ormore points to the electrical power control operations provided by thehandle assembly 4102. For example, in certain forms, the surgicalinstrument may comprise a rotatable electrical connection allowing theelectrical power control operations provided by the handle assembly 4102to electrically communicate with the generator 4116 via the ultrasonichand piece 4114. That is, in one form, the handle assembly 4102 and theultrasonic hand piece 4114 are electrically coupled via a rotatableelectrical connection of a connector module 4190.

FIG. 96 illustrates a connector module 4200 according to various forms.The connector module 4200 is shown coupled to a flex circuit 4202 and adistal portion 4204 of a hand piece 4114, which is also shown in anisolated view in the hatched box. The connector module 4200 comprises ahousing 4206 and a rotation coupling 4208. Although not shown, theconnector module 4200 and ultrasonic hand piece 4114 may be positionedwithin the opening 4156 the handle assembly 4102 such that theultrasonic hand piece 4114 or waveguide 4128 is positioned within acentral bore 4210 defined by the housing 4206 and a distal portion 4204of the hand piece is thereby received and engaged by the connectormodule 4200. As described above, the ultrasonic hand piece 4114 maymechanically and acoustically couple to the waveguide 4128, which may bestructured to operably couple to an end effector assembly 4112. Theultrasonic hand piece 4114 may also be rotatable relative to the housing4206 of the connector module 4200, which may provide a rotatableelectrical connection between the ultrasonic hand piece 4114 and acontrol or user interface circuit comprising a user interface, such asthe switch assembly 4108 operatively associated with the flex circuit4202.

In the illustrated form, the control or user interface circuit comprisesthe flex circuit 4202. For example, the rotatable electrical connectionmay comprise an electrical communication or conductive path along whichelectrical control operating instructions or signals provided by a userat a user interface, e.g., via the switch assembly 4108, may beelectrically coupled to the generator 4116, e.g., via the ultrasonichand piece 4114. Accordingly, the electrical control operatinginstructions or signals may be received by the generator 4116, which mayrespond by altering power delivery to the ultrasonic hand piece 4114 tocontrol the operation of the instrument 4100. Further to the above, theswitch assembly 4108 may comprise or be electrically coupled to the flexcircuit 4202, which in turn may be configured to provide anelectro-mechanical interface between the switches 4132 a, 4132 b and thegenerator 4116 via the hand piece 4114. For example, the flex circuit4202 may comprise one or more switch points 4202 a, 4202 b configuredfor mechanical actuation via the toggle switches 4132 a, 4132 b. In oneform, the flex circuit 4202 may comprise electrical contact switches,such as dome switches, that may be depressed to provide an electricalsignal to the generator 4116. The flex circuit 4202 may comprise one ormore conductors, such as conductive pathways, shown generally as 4211,which may be provided by wires, traces, or other conductive pathways asis known to those in the art. The conductive pathways may electricallycouple to one or more switch conductors or ring conductors 4212, 4214,as shown in the exploded view of the connector module 4200 in FIG. 97.The flex circuit 4202 may couple to the ring conductors 4212, 4214 viaone or more conductive leads 4216, 4218 or tabs of the respectivedelivery ring conductors 4212, 4214 (described below). It is to beappreciated that while switch conductors are generally referred toherein as ring conductors 4212, 4214 that define generally arcuatestructures or bodies that may comprise one or more conductive paths, invarious forms, the switch conductors may comprise other structures suchas arcuate tracks, for example.

The connector module 4200 comprises an outer ring conductor 4212 and aninner ring conductor 4214. The outer ring conductor 4212 and the innerring conductor 4214 each define a generally open-ended O-shapedstructure and are configured for relative rotation with respect to thehand piece 4114. Each of the outer and inner ring conductors 4212, 4214may further comprise a conductive connection, e.g., a lead 4216, 4218,that may be electrically coupled to the flex circuit 4202 via one ormore conductive pathways 4211, thereby providing a conductive path tothe connector module 4200 for rotatable electrical communication to thegenerator 4116 via the hand piece 4114. Accordingly, a control circuitmay be established wherein the connector module 4200 provides arotatable electrical connection between the user interface, e.g., switchassembly 4108, and the hand piece 4114.

Referring generally to FIG. 97, in various forms, one or more links4220, 4222 a, 4222 b may be positioned to be movable relative to and/oralong a portion of a ring conductor 4212, 4214 comprising a conductivepath. For example, a link 4220, 4222 a, 4222 b may be rotationallycoupled to the ultrasonic hand piece 4114 when the hand piece 4114 isreceived within the opening 4156 to engage the connector module 4200.The rotation of the ultrasonic hand piece 4114 in direction 4170 (seeFIG. 93) may produce a corresponding rotation of the link 4220, 4222 a,4222 b about the longitudinal axis “T” with respect to a correspondingring conductor 4212, 4214 between a first position and a secondposition. The link 4220, 4222 a, 4222 b may comprise one or moreconductor contacts 4224 a, 4224 b, 4226 a, 4226 b positioned toelectrically couple to the corresponding ring conductor 4212, 4214 whenthe link 4220, 4222 a, 4222 b is in the first position and the secondposition. The link 4220, 4222 a, 4222 b may further comprise one or morehand piece coupling contacts 4228 a, 4228 b, 4230 a, 4230 b configuredto electrically couple to a distal surface 4232 a, 4232 b, 4234 a, 4234b of the distal portion 4204 of the ultrasonic hand piece 4114 when thelink 4220, 4222 a, 4222 b is in the first position and the secondposition.

Further to the above, in various forms, the links 4220, 4220 a, 4220 amay be rotatable relative to a respective ring conductor 4212, 4214. Thering conductor contacts 4224 a, 4224 b, 4226 a, 4226 b may be positionedto rotate about or along a surface of the ring conductors 4212, 4214when the hand piece 4114 rotates with relative to the housing 4206. Inone form, the ring conductors 4212, 4214 comprise arcuate surfaces ortracks about which the ring conductor contacts 4224 a, 4224 b, 4226 a,4226 b may rotationally contact through an arcuate rotation extendingfrom or between a first position and a second position. For example, insome forms, the ring conductor contacts 4224 a, 4224 b, 4226 a, 4226 bmay comprise pressure contacts configured for pressure contact with arespective ring conductor 4212, 4214 along an arcuate conductive path.In one form, one or more links 4220, 4222 a, 4222 b comprise atensioning member, such as a spring arm 4236 a, 4236 b, 4238 a, 4238 b,to tension or bias one or more ring conductor contacts 4224 a, 4224 b,4226 a, 4226 b toward a ring conductor 4212, 4214 to maintain electricalcoupling with respect to the ring conductor 4212, 4214 when the link4220, 4222 a, 4222 b rotates relative to the ring conductor 4212, 4214.In certain forms, the ring conductor contacts 4224 a, 4224 b, 4226 a,4226 b may be biased against an inner or outer surface of the ringconductor 4212, 4214 such that the ring conductor may electricallycouple the link 4220, 4222 a, 4222 b with the ring conductor 4212, 4214along one or more portions of an arcuate motion associated with theultrasonic hand piece and/or a corresponding link 4220, 4222 a, 4222 b.In other forms, for example, the link 4212, 4214 may comprise a ringconductor contact 4224 a, 4224 b, 4226 a, 4226 b that may be engageablewith the ring conductor 4212, 4214 along a conductive path via a hookedor looped portion about or around the ring conductor 4212, 4214.

Referring generally to FIG. 98, showing an operational arrangement ofthe links 4220, 4222 a, 4222 b and corresponding ring conductor 4212,4214, the connector module may comprise an outer ring conductor 4212 andan inner ring conductor 4214. In various forms, each ring conductor4212, 4214 may also define a conductive path along an arcuate portion ofthe ring conductor 4212, 4214. An outer link 4220 may be provided thatis configured for rotation relative to or about the outer ring conductor4212. An inner link 4222 a, 4222 b may similarly be configured forrotation relative to or about the inner ring conductor 4214. Forexample, the outer ring conductor 4212 and the inner ring conductor 4214may comprises conductive leads 4216, 4218 configured to electricallyconnect to the flex circuit 4202 through slots 4242, 4244 defined in thehousing 4206. In one form, the conductive leads 4216, 4218 may at leastpartially retain the outer ring conductor 4212 and the inner ringconductor 4214 to allow relative rotation with respect to the links4220, 4222 a, 4222 b. Each link 4220, 4222 a, 4222 b may comprise one ormore conductor contacts 4224 a, 4224 b, 4226 a, 4226 b positioned toelectrically couple to a corresponding ring conductor 4212, 4214 whenthe link 4220, 4222 a, 4222 b is in the first position and the secondposition. Each link 4220, 4222 a, 422 b may comprise one or more handpiece coupling contacts 4228 a, 4228 b, 4230 a, 4230 b configured toelectrically couple to a distal surface 4232 a, 4232 b, 4234 a, 4234 bof the distal portion 4204 of the ultrasonic hand piece 4114. Forexample, the ring conductor contacts 4224 a, 4224 b, 4226 a, 4226 b maybe rotated about the longitudinal axis between a first position and asecond position such that the ring conductor contacts 4224 a, 4224 b,4226 a, 4226 b maintain electrical contact with the corresponding ringconductor 4212, 4214 through the rotation.

The outer link may comprise a pair of ring conductor contacts 4224 a,4224 b that may be coupled to spring arms 4236 a, 4236 b to bias thecontacts 4224 a, 4224 b toward an inner surface of the outer ring 4212.In one form, the inner link 4214 comprises a pair of ring conductorcontacts 4226 a, 4226 b attached to spring arms 4238 a, 4238 bstructured to bias the contacts 4226 a, 4226 b toward an outer surfaceof the inner ring 4214. The inner link 4222 a, 4222 b comprises a firstportion 4222 a and second portion 4222 b, however, in certain forms, theinner link 4222 a, 4222 b may comprise a unitary structure. For example,the inner link 4222 a, 4222 b may comprise a conductive ornon-conductive body portion extending between the pair of ring conductorcontacts 4226 a, 4226 b.

As introduced above, in various forms, a connector module 4202 comprisesone or more links 4220, 4222 a, 4222 b positioned to rotate relative toa handle assembly, a housing 4206, a user interface 4108, a trigger4120, and or a conductive path associated with a ring conductor 4212,4214 (see FIGS. 94, 98-99). According to various forms, the links 4220,4222 a, 4222 b comprise one or more hand piece coupling contacts 4228 a,4228 b, 4230 a, 4230 b structured to engage and electrically couple tothe distal portion 4204 of ultrasonic hand piece 4114 (FIG. 96). In oneform, the hand piece coupling contacts 4228 a, 4228 b, 4230 a, 4230 bmay comprise an engagement member structured to engage the distalportion 4204 of ultrasonic hand piece 4114 to at least partiallyrotationally couple the respective link 4220, 4222 a, 4222 b to theultrasonic hand piece 4114.

In one form, the outer link 4220 comprises a pair of outer hand piececoupling contacts 4228 a, 4228 b electrically coupled with the pair ofouter ring contacts 4224 a, 4224 b to provide an electrical conductivepath from the distal portion of the hand piece to the outer ringconductor 4212. Each of the pair of hand piece coupling contacts 4228 a,4228 b is structured to extend through a respective slot 4246 a, 4246 bdefined in the rotation coupling 4210. As explained in more detailbelow, the rotation coupling 4210 may be configured to couple with therotation of the ultrasonic hand piece 4114. For example, in variousforms, the rotation coupling 4210 is configured to provide a rotatableframework to couple the rotation of the ultrasonic hand piece 4114 tothe links 4220, 4222 a, 4222 b.

The pair of hand piece coupling contacts 4228, 4228 b illustrated inFIG. 98 comprise curved extensions structured to engage and electricallycouple to one or more electrical contacts disposed along a first distalsurface 4232 a, 4232 b of the of the ultrasonic hand piece 4114. Asillustrated, the curved extensions of the pair of outer hand piececoupling contacts 4228 a, 4228 b may operate to at least partiallyassist in coupling the rotation of the ultrasonic hand piece 4114 toeffect a corresponding rotation to the outer link 4220. For example, thecurved extensions may comprise an engagement member comprising an edgestructured to frictionally engage the first distal surface 4232 a, 4232b or be positionable within a groove or edge defined in the first distalsurface 4232 a, 4232 b to rotationally couple the ultrasonic hand piece4114 and the rotation coupling 4210. In certain forms, the outer handpiece coupling contacts 4228 a, 4228 b extend from tensioning members orspring arms 4248 a, 4248 b configured to bias or tension the outer handpiece coupling contacts 4228 a, 4228 b outward of the longitudinal axis“T” and/or toward the first distal surface 4232 a, 4232 b. In one form,the outer link 4220 comprises one or more tabs 4250 a, 4250 b, such asprojections or clips, structured to retain the link 4220. For example,first tab 4250 a may be received in slot 4252 defined in the rotationcoupling 4208 and a second tab 4250 b may clip to and/or be compressibleagainst a portion of the rotation coupling 4208 to retain a position ororientation of the link 4220 (FIG. 100).

In one form, the inner link 4222 a, 4222 b comprises a pair of innerhand piece coupling contacts 4230 a, 4230 b electrically coupled to thepair of inner ring conductor contacts 4226 a, 4226 b to provide anelectrical conductive path from the ultrasonic hand piece 4114 to theinner ring conductor 4214. The pair of outer hand piece couplingcontacts 4230 a, 4230 b are each structured to extend through a slot4254 a, 4254 b defined in the rotation coupling 4210 and comprise curvedextensions defining edges structured to engage and electrically coupleto one or more electrical contacts disposed along a second distalsurface 4234 a, 4234 b of the distal portion 4204 of the ultrasonic handpiece 4114. As illustrated, the curved extensions may operate to atleast partially assist in coupling the rotation of the ultrasonic handpiece 4114 (FIG. 96) to effect a corresponding rotation to the innerlink 4222 a, 4222 b. For example, the curved extensions may compriseengagement members structured to frictionally engage the second distalsurface 4234 a, 4234 b or be positionable within a groove or edgedefined in the second distal surface 4234 a, 4234 b to rotationallycouple with the rotation of the ultrasonic hand piece 4114. In variousforms, the inner hand piece coupling contacts 4230 a, 4230 b extend fromtensioning members comprising spring arms 4258 a, 4258 b configured toprovide a bias or tension the hand piece coupling contacts 4230 a, 4230b outward of the longitudinal axis “T” and/or toward the second distalsurface 4234 a, 4234 b of the hand piece 4114. In various forms, theinner link 4220 a, 4220 b further comprises one or more tabs 4256 a,4256 b to retain the link in a desired orientation. For example, theinner link 4220 a, 4220 b may comprise a first tab 4256 a and second tab4256 b. The first and second tabs 4256 a, 4256 b may be configured to bereceived in a slot defined in the rotation coupling 4210 or clip toand/or compress against a portion of the rotation coupling 4210 (notshown).

In various forms, the distal portion 4204 of the ultrasonic hand piece4114 may comprise one or more distal contact surfaces 4232 a, 4232 b,4234 a, 4234 b, shown generally in the hatched isolation window of FIG.96. The distal contact surfaces 4232 a, 4232 b, 4234 a, 4234 b mayprovide electrical contacts or contact points that may electricallycouple to the ring conductors 4212, 4214 via links 4220, 4222 a, 4222 b.In some forms, electrically coupling the hand piece 4114 with the ringconductors 4212, 4214 may complete an electrical circuit comprising auser interface circuit, such as the flex circuit 4202, and the generator4116, as described above.

In one form, the hand piece 4114 may comprise distal contact surfaces4232 a, 4232 b, 4234 a, 4234 b disposed on or within a distal rim 4205positioned along the distal portion 4204 of the hand piece 4114. Thedistal rim 4205 may define one or grooves defining the distal contactsurfaces 4232 a, 4232 b, 4234 a, 4234 b comprising one or moreelectrical contacts or contact surfaces. The contact surfaces maycomprise, for example, gold plating or other suitable conductiveelectrical contact material known in the art. In one form, this distalrim 4205 may define longitudinal or circumferential grooves dimensionedto complement or receive a hand piece coupling contact 4228 a, 4228 b,4230 a, 4230 b. For example the distal rim 4205 may define one or moregrooves along the distal contact surfaces 4232 a, 4232 b, 4234 a, 4234 bto fittably engage a respective hand piece coupling contact 4228 a, 4228b, 4230 a, 4230 b such that the distal contact surfaces 4232 a, 4232 b,4234 a, 4234 b and respective hand piece coupling contacts 4228 a, 4228b, 4230 a, 4230 b may frictionally, electrically, and rotationallycoupled when the connector module 4200 receives the hand piece 4114. Inone form, the distal contact surfaces 4232 a, 4232 b, 4234 a, 4234 b andthe respective hand piece coupling contacts 4228 a, 4228 b, 4230 a, 4230b may couple in a male-female or lock-and-key relationship. In certainforms, the distal contact surfaces 4232 a, 4232 b, 4234 a, 4234 bcomprise on or more circumferential ridges extending about an innercircumference of the distal rim 4205 to electrically couple withrespective hand piece coupling contacts 4228 a, 4228 b, 4230 a, 4230 balong all or part of the circumferential ridges. In various forms, thedistal contact surfaces 4232 a, 4232 b, 4234 a, 4234 b comprise goldplated circumferential electrical contacts disposed on thecircumferential ridges within the inner surface of the distal rim 4205,as shown in FIG. 96.

The distal contact surfaces 4232 a, 4232 b, 4234 a, 4234 b may beelectrically coupled to the generator 4116 via leads extending throughthe hand piece 4114 and wire 4118 to communicating electrical controlsignals from the user interface, e.g., the switch assembly 4108, tocontrol an operation of the ultrasonic surgical instrument 4100.Accordingly, in one form, the flex circuit 4202 may be configured tointerface with the switches 4132 a, 4132 b and to provide electricalsignals along the conductive pathways 4211 to the conductive leads 4216,4218, which in turn provide electrical connection to the links 4220,4222 a, 4222 b via the ring conductors 4212, 4214, which in turnelectrically couple, via the hand piece coupling contacts 4228 a, 4228b, 4230 a, 4230 b, to distal contact surfaces 4232 a, 4232 b, 4234 a,4234 b disposed at the distal portion of the ultrasonic hand piece 4114to provide a conductive path to the generator 4116 via the ultrasonichand piece 4114 a cable 4118.

According to various forms, the connector module 4202 comprises aspindle 4240. The spindle may extend from the housing 606 along thelongitudinal axis “T” and may define a central bore 4210 along thelongitudinal axis “T” dimensioned to receive a length of the hand piece4114 and/or waveguide 4128 therethrough. As shown in FIGS. 96-97, thespindle extends proximally from the housing 4206 along the longitudinalaxis “T”. The rotation coupling 4208 is rotatably mounted on the spindle4240 for rotation about the longitudinal axis “T” with relative to thehousing 4206. In certain forms, the spindle 4240 comprises one or moreretaining structures 4260 a, 4260 b structured to retain and thereforelimit the longitudinal excursion of the rotation coupling 4208.

FIG. 99 illustrates the ring conductors 4212, 4214 mounted to orotherwise positioned with respect to the housing 4206 such the handpiece 4114 may rotate relative to the ring conductors 4212, 4214. One ormore portions of the ring conductors 4212, 4214 may extend through slotsdefined in the housing 4206 to provide an anchorage with respect to thehousing 4206. As describe above, the ring conductors 4212, 4214 maycomprise leads 4216, 4218 extending through slots 4242, 4244 defined inthe housing. As shown in FIG. 97 and FIG. 99, the outer ring conductor4212 includes two tabs 4262 a, 4262 b dimensioned to be received withintwo retention slots 4264 a, 4264 b defined in the housing 4206. Invarious forms, the ring conductors 4212, 4214 and/or housing maycomprise additional positioning features such as hooks, latches, clips,or adhesives, for example, that may be used to position the ringconductors 4212, 4214 proximate to the housing 4206 to allow relativerotation between the ultrasonic hand piece 4114 and the ring conductors4212, 4214. In FIG. 99, the inner ring conductor 4214 comprises an innercircumference 4266 (see FIG. 97) configured to fittably engage a surface4268 extending from the housing 4206. In one form, the inner ringconductor 4212 may be frictionally and/or adhered with an adhesive tothe surface 4268.

FIG. 100 illustrates a perspective view of a distal portion of therotation coupling 4210 having therein positioned inner and outer ringconductors 4212, 4214 and corresponding inner and outer links 4220, 4222a, 4222 b. The rotation coupling 4210 comprises a plurality of internalslots configured to receive and therein retain the inner and outer links4220, 4222 a, 4222 b. It is to be appreciated that various forms maycomprise other slot configuration than shown in FIG. 100. For example,in various forms, the rotation coupling may contain positioningextensions to position the links. In one form, one or more portions ofthe links 4220, 4222 a, 4222 b may be adhered to the rotation couplingby an adhesive. In the illustrated form, the rotation coupling comprisesan outer slot 4270 a, 4270 b, 4270 c for receiving the outer ringconductor 4212. The outer slot 4270 a, 4270 b, 4270 c may be dimensionedto allow relative rotation between the rotation coupling 4210 and theouter ring conductor 4212. The rotation coupling 4210 may further defineslot 4280 for receiving the outer link 4220. Slot 4280 is positionedinward toward the longitudinal axis “T” (see FIG. 96) with respect toouter slot 4270 a, 4270 b, 4270 c. Slot 4280 comprises spring arm slots4282 a, 4282 b dimensioned for receiving spring arms 4236 a, 4248 a and4236 b, 4248 b, respectively. Adjacent to the spring arm slots 4282 a,4282 b, slot 4280 defines slots 4284 a, 4284 b, which are dimensioned toreceive outer ring conductor contacts 4224 a, 4224 b, respectively. Slot4280 further defines slots 4286 a, 4286 b, which are dimensioned toreceive the outer hand piece coupling contacts 4228 a, 4228 b and extendproximally to slots 4246 a, 4246 b (slot 4246 b is shown in FIG. 96).The rotation coupling 4210 may further define slot 4296 b for receivingthe inner ring conductor 4214 and slot 4281 for receiving the inner link4222 a, 4222 b. Slot 4281 is positioned inward toward the longitudinalaxis “T” (see FIG. 96) with respect to spring arm slots 4288 a, 4288 band is dimensioned to receive spring arms 4238 a, 4238 b, respectively.Adjacent to one end of each spring arm slots 4288 a, 4288 b, therotation coupling defines an inner ring contact slot 4290 a, 4290 b forreceiving the inner ring contacts 4226 a, 4226 b, respectively. Adjacentto the other end of each spring arm slots 4288 a, 4288 b, the rotationcoupling defines slots 4292 a, 4292 b, which are dimensioned to receiveinner hand piece coupling contacts 4230 a, 4230 b, respectively, andrespectively extend proximally to slots 4254 a, 4254 b (slot 4254 b isshown in FIG. 96).

The rotation coupling further defines a bore 4294 dimensioned to bemounted about the spindle 4240. A proximal inner circumferential surface4296 a of the rotation coupling defines a portion of the bore 4294 thatcomprises a decreased diameter relative to a more distal innercircumferential surface that defines slot 4296 b. The decreased diameterof the proximal inner circumferential surface defining slot 4296 a mayreduce rotational friction about the spindle 4240 and may provideadditional space for components, such as ring conductors 4212, 4214 andlinks 4220, 4222 a, 4222 b, to be positioned about the spindle 4240within the rotational coupling 4210. The rotational coupling 4210further includes a proximal outer circumferential surface 4298 acomprising a decreased diameter relative to a distal outercircumferential surface 4298 b. The decreased diameter of the distalouter circumferential surface 4298 a may provide additional space forcomponents, such as ring conductors 4212, 4214 and links 4220, 4222 a,4222 b, to be positioned about the spindle 4240 within the rotationalcoupling 4210. It is to be appreciated that additional ring conductorsand links may be provided to, for example, provide additional rotatableelectrical connections.

FIGS. 101-103 illustrate a connector module 4300 according to variousforms. In one form, the connector module may find use in ultrasonicsurgical instruments similar to that described above with respect toFIGS. 96-99. Therefore, for brevity, similar features and may beidentified by similar numbers and may not be described in similardetail. However, it is to be understood that the various features mayfind similar use and share similar descriptions as those presented abovewith respect to connector module 4190 and connector module 4200 andultrasonic surgical instrument 4100. For example, the connector module4300 may be coupled to a circuit associated with a user interface, whichmay be similar to flex circuit 4202. The connector module 4300 may alsocouple to a distal portion 4304 of an ultrasonic hand piece (see FIGS.93-94). The connector module 4300 comprises a housing 4306 and arotation coupling 4308 and may be positionable within a handle assembly(e.g., handle assembly 4102 shown in FIGS. 93-95). As described above,the ultrasonic hand piece may mechanically and acoustically couple to awaveguide, which may be structured to operably couple to an end effectorassembly. The ultrasonic hand piece may also be rotatable relative tothe connector module housing 4306, which may provide a rotatableelectrical connection between the ultrasonic hand piece and the userinterface. The connector module 4300 may include a spindle 4340extending generally proximally from the housing 4306 along alongitudinal axis. The rotation coupling 4308 may be rotatably mountedon the spindle 4340 for rotation thereabout with respect to the housing4306. The spindle 4340 includes one or more retaining structures 4360 a,4360 b structured to retain and therefore limit the longitudinalexcursion of the rotation coupling 4308.

The switch assembly 4300 includes a pair of outer hand piece couplingcontacts 4328, 4328 b comprising pressure contacts structured toelectrically couple to one or more electrical contacts disposed along afirst distal surface 4332 a, 4332 b of the of the ultrasonic hand piece.The outer hand piece coupling contacts 4328 a, 4328 b may extend fromtensioning members or spring arms 4348 a, 4348 b (see FIG. 103)configured to bias or tension the outer hand piece coupling contacts4328 a, 4328 b outward of the longitudinal axis and/or toward the firstdistal surface 4332 a, 4323 b. The outer hand piece coupling contacts4328 a, 4328 b may be structured to respectively extend through a slot4346 a, 4346 b defined in the rotation coupling 4310 and comprisepressure contacts structured to electrically couple to one or moreelectrical contacts disposed along a first distal surface 4332 a, 4332 bof the distal portion 4304 of the ultrasonic hand piece.

In one form, the switch assembly 4300 includes a pair of inner handpiece coupling contacts 4330 a, 4330 b comprising pressure contactsstructured to electrically couple to one or more electrical contactsdisposed along a second distal surface 4334 a, 4334 b of the of theultrasonic hand piece. The inner hand piece coupling contacts 4330 a,4330 b may extend from tensioning members or spring arms 4358 a, 4358 b(see FIG. 103) configured to bias or tension the inner hand piececoupling contacts 4330 a, 4330 b outward of the longitudinal axis and/ortoward the second distal surface 4334 a, 4334 b. The outer hand piececoupling contacts 4330 a, 4330 b may be structured to respectivelyextend through a slot 4354 a, 4354 b defined in the rotation coupling4310 and comprise pressure contacts structured to electrically couple toone or more electrical contacts disposed along a second distal surface4334 a, 4334 b of the distal portion 4304 of the ultrasonic hand piece.

As shown most clearly in FIGS. 101-102, the connector module 4300comprises one or more engagement features 4399 a, 4399 b, 4399 c, 4399 dstructured to engage the ultrasonic hand piece. The engagement features4399 a, 4399 b, 4399 c, 4399 d may comprise one or more projections,clips, or “grippers” formed about the rotation coupling 4310. Theengagement features 4399 a, 4399 b, 4399 c, 4399 d are structured tofittably engage a surface of the ultrasonic hand piece. The engagementfeatures may comprise one or more pliable, resilient, flexible polymericmaterials positioned on the rotation coupling. In one form, theengagement features 4399 a, 4399 b, 4399 c, 4399 d are dimensioned togrip a diameter of the ultrasonic instrument. For example, theengagement features 4399 a, 4399 b, 4399 c, 4399 d may define a diameterthat is undersized relative to a dimension of the ultrasonic hand pieceto create a friction interference fit. In various forms, the hand piecemay comprise a distal portion 4304 defining a ridge or groove configuredto receive a portion of the engagement features 4399 a, 4399 b, 4399 c,4399 d. In one form, the engagement 4399 a, 4399 b, 4399 c, 4399 d maybe configured to flex inward toward the longitudinal axis to receive thehand piece while providing tension outward of the longitudinal axis torotationally couple with the hand piece when the hand piece has beenreceived.

FIG. 103 illustrates a distal view of the rotation coupling 4310 havingtherein disposed inner and outer ring conductors 4312, 4314 andcorresponding inner and outer links 4320, 4322 a, 4322 b. The inner andouter links 4320, 4322 a, 4322 b are rotatable relative to the outerring conductor 4312 and an inner ring conductor 4314. The outer ringconductor 4312 and the inner ring conductor 4314 comprises conductiveleads 4316, 4318 configured to electrically connect to a user interfacethrough slots defined in the housing 4306, which may be similar to slots4342, 4344. Each link 4320, 4322 a, 4322 b comprises a pair or conductorcontacts 4324 a, 4324 b, 4326 a, 4326 b positioned to electricallycouple to the corresponding ring conductor 4312, 4314 when the link4320, 4322 a, 4322 b is in the first position and the second positionand a pair of hand piece coupling contacts 4328 a, 4328 b, 4330 a, 4330b configured to electrically couple to a distal surface 4332 a, 4332 b,4334 a, 4334 b of the distal portion 4304 of the ultrasonic hand piece.For example, the ring conductor contacts 4324 a, 4324 b, 4326 a, 4326 bmay be rotated about a longitudinal axis between a first position and asecond position such that the ring conductor contacts 4324 a, 4324 b,4326 a, 4326 b maintain electrical contact with the corresponding ringconductor 4312, 4314 through the rotation.

The outer link 4312 comprises a pair of ring conductor contacts 4324 a,4324 b coupled to spring arms 4336 a, 4336 b structured to bias thecontacts 4324 a, 4324 b toward an inner surface of the outer ring 4312.The pair of outer hand piece coupling contacts 4328 a, 4328 belectrically coupled with the pair of outer ring contacts 4324 a, 4324 bto provide an electrical conductive path from the distal portion 4304 ofthe hand piece to the outer ring. The inner link 4314 comprises a pairof ring conductor contacts 4326 a, 4326 b electrically coupled to thepair of hand piece coupling contacts 4320 a, 4320 b and are attached tospring arms 4338 a, 4338 b structured to bias the ring conductorcontacts 4326 a, 4326 b toward an outer surface of the inner ring 4314.The inner link 4322 a, 4322 b comprises a first portion 4322 a andsecond portion 4322 b.

The rotation coupling 4310 forms a central bore 4394 defined by aproximal rotation surface 4396 a and a distal slot 4396 b. The rotationcoupling 4310 comprises a plurality of slots dimensioned to receive thering conductors 4312, 4314 and corresponding links 4320, 4322 a, 4322 b.The slot configuration shown in FIG. 103 is similar to the slotconfiguration shown in FIG. 100 and, for brevity, will not be describedin detail. For example, the rotation coupling comprises slot 4370 toreceive the outer ring conductor 4312 and slot 4396 b to receive innerring conductor 4314. The rotation coupling defines slot 4380, which isdimensioned to receive the outer link 4312. The rotation coupling alsodefines slot 4388 a to receive the first portion of the inner link 4322a and slot 4388 b to receive the second portion of the inner link 4322b. Slots 4346 a, 4346 b comprise circumferential window facing outwardof the longitudinal axis. Slots 4392 a, 4392 b define outward facingarcuate grooves structure to receive the inner hand piece couplingcontacts 4330 a, 4320 b.

FIGS. 104 and 105 illustrate one form of a handle assembly 5000 thatemploys a unique and novel switch assembly, generally designated as5020. In various forms, the handle assembly 5000 may be similar indesign and use to other handle assemblies disclosed herein. Accordinglythose features that are common to other handle assembly arrangementsthat have been described above will not be discussed in detail beyondthat which may be necessary to understand the design and operation ofhandle assembly 5000.

In at least one form, the handle assembly 5000 may comprise two handlehousing segments that are configured to be coupled together to form ahandle housing 5002. For example, a left handle housing segment 5004 isshown in FIG. 104 and a right handle housing segment 5006 is shown inFIG. 105. The handle housing segments 5004, 5006 may each be fabricatedfrom a plastic or other polymer material and be coupled together byfasteners such as screws, bolts, snap features, adhesive, etc. Thehandle housing segments 5004, 5006 cooperate to form a handle housing5002 that has a “fixed” handle portion that may form a pistol grip 5008that may be easily gripped and manipulated by one hand. As can be seenin FIG. 104, the left handle housing segment 5004 may be contoured insuch a manner so as to establish a “thumb groove” area, generallydesignated as 5010. Those of ordinary skill in the art will readilyappreciate that when a clinician is gripping the pistol grip 5008 in hisor her right hand, for example, the clinician's thumb may be naturallylocated in the thumb groove area 5010. In at least one form, the righthandle housing 5006 may also be formed with a similar thumb groove area(not shown), such that if the clinician is gripping the handle assembly5000 in his or her left hand, the clinician's left thumb would naturallybe located in that area.

As indicated above, the handle assembly 5000 includes a switch assembly5020 that may include a first switch arrangement 5030 and a secondswitch arrangement 5060. In at least one form, the first switch 5030includes a first button assembly 5032 that is supported for pivotaltravel relative to a “forward portion” 5003 of the handle housing 5002.The first button assembly 5032 may be formed from, for example, apolymer or other suitable material and include a first finger button5034 and a second finger button 5036 that are interconnected by ajournal portion 5038. The journal portion 5038 serves to pivotallysupport the first button assembly 5032 on a first pivot pin 5040 thatextends between the left and right housing segments 5004, 5006. Thefirst pivot pin 5040 may be molded into one of the housing segments5004, 5006 and be received in a corresponding socket (not shown) formedin the other housing segment 5004, 5006. The first pivot pin 5040 may beattached to the handle housing segments 5004, 5006, by other means aswell. The first pivot pin 5040 defines a first switch axis FS-FS aboutwhich the first button assembly 5032 may be “rocked”. See FIG. 107. Inat least one form, the first and second finger buttons 5034, 5036 may beprovided with a somewhat “bulbous” shape as shown in FIGS. 106 and 107.In addition, to further enhance the clinician's ability to distinguishbetween the first finger button 5034 and second finger button 5036without looking directly at the finger buttons 5034, 5036, one of thefinger buttons may be provided with a distinguishing feature orfeatures. For example, as shown in FIGS. 106 and 107, the first fingerbutton 5034 has a plurality of detents 5042 or other formations formedinto its perimeter.

As can be seen in FIG. 105, a switch frame 5050 is supported within thehandle assembly 5002 such that it is located proximal to the firstbutton assembly 5032 and in the portion of the housing assembly 5002that is adjacent to the thumb groove area 5010 (FIG. 104). In one form,the switch frame 5050 is non-movable relative to the first buttonassembly 5032 and may be rigidly supported on stand-offs or othergusset-like support features molded into or otherwise formed on thehandle housing segments 5004, 5006. The switch frame 5050 may support acircuit board 5052, e.g., a printed circuit board, flex circuit,rigid-flex circuit, or other suitable configuration that includes afirst contact pad 5054 that corresponds to the first finger button 5034and a second contact pad 5056 that corresponds to the second fingerbutton 5036. Those of ordinary skill in the art will understand that byrocking or pivoting the first button assembly 5032 about the firstswitch axis FS-FS, the clinician can activate the first contact pad 5054by pivoting the first finger button 5034 into actuation contact with thefirst contact pad 5054. As used herein, the term “actuation contact” mayinclude a sufficient amount of physical contact between the fingerbutton and the first contact pad required to initiate actuation of thecontact pad (or similar contact arrangement). “Actuation contact” mayalso include a sufficient amount of physical proximity of the fingerbutton relative to the contact pad (or other contact arrangement) thatis sufficient to initiate actuation of the contact pad—but without anyportion of the finger button actually physically touching the contactpad. The clinician can activate the second contact pad 5056 by pivotingthe second finger button 5036 into actuation contact with the secondcontact pad 5056. Such unique and novel first switch arrangement may beeasily actuated by the clinician's index finger when her or she isgripping the pistol grip portion 5008 of the handle assembly 5000. Thus,every button of the switch assembly may be easily actuated by the singlehand supporting the handle assembly. As in the various forms describedabove, the first switch arrangement 5030 may be employed to modulate thepower setting of the ultrasonic handpiece and/or to active variousalgorithms described herein.

In some forms, the first switch arrangement 5030 is coupled to agenerator, such as any of the generators 30, 500, 1002. For example, therespective contact pads 5054, 5056 may be in electrical communicationwith the generator via a connector module 5057, which, in some forms, issimilar to the connector module 4200 described herein above. Theconnector module 5057 is coupled to an internal or external generator.Signals indicating activation of the respective contact pads 5054, 5056may cause the generator to modify the operation of the instrument 5000.For example, when the clinician selects the first finger button 5034, itmay cause the generator to increase the level of power provided to theend effector. When the clinician selects the second finger button 5036,it may cause the generator to decrease the level of power provided tothe end effector. In various embodiments, the generator may beconfigurable between a minimum power level (e.g., MIN) and maximum powerlevel (e.g., MAX). For example, some forms of the GEN11 generatoravailable from Ethicon Endo-Surgery, Inc. of Cincinnati Ohio providefive power levels. The finger buttons may be used to toggle thegenerator among the power levels. Also, in some forms, one or both ofthe finger buttons 5034, 5036 may be associated with an algorithm, suchas those described herein. For example, when the user selects one of thebuttons 5034, the generator may execute an algorithm, such as, forexample, one or more of algorithms 3021, 3021′, 3021″, 3120, 3170 any ofthe algorithms described with respect to FIGS. 15A-15C, 20-22, 57-60,etc.

In various forms, the switch assembly 5020 also includes a second switcharrangement 5060. Referring to FIGS. 107-109, the second switcharrangement 5060 may include a right switch button 5062 and a leftswitch button 5066 that are each pivotally attached to the switch frame5050. For example, the right switch button 5062 is pivotally attached toor pinned to the switch frame 5050 for selective pivotal travel about aright switch axis RS-RS that is substantially transverse to the firstswitch axis FS-FS. See FIGS. 108 and 109. Likewise, the left switchbutton 5066 is pivotally attached to the switch frame 5050 for selectivepivotal travel about a left switch axis LS-LS. In alternativearrangements, the right and left switch buttons 5062, 5066 may bepivotally supported by the handle housing segments 5004, 5006.

In at least one form, the right and left buttons 5062 and 5066 may havea general “barrel-shape” to facilitate ease of actuation by theclinician's thumb and/or finger. This ease of actuation is furtherenhanced by the fact that the right and left buttons 5062, 5066 arestrategically located in the general thumb groove areas associated witheach handle housing segment. For example, if the clinician is holdingthe pistol grip 5008 in his or her right hand, the clinician mayactivate the right switch button 5062 by sweeping his or her right thumbdown across the right switch button 5062 in a contacting sweepingmotion. Similarly, if the clinician was holding the pistol grip 5008 inhis or her left hand, he or she may activate the left switch button 5066by sweeping her left thumb down across the left switch button 5066 in acontacting sweeping motion. Such unique and novel switch arrangementsenable activation of the left and right switch buttons 5062, 5066 byavoiding inadvertent activation from direct inward forces to the switchbuttons.

As can be seen in FIG. 108, the right switch button 5062 has a rightswitch arm 5064 protruding therefrom for actuating a right contact pad5058 that comprises a portion of the circuit board 5052. Likewise, theleft switch button 5062 has a left switch arm 5068 protruding therefromfor actuating a left contact pad 5059 that comprises a portion of thecircuit board 5052. Thus, those of ordinary skill in the art willunderstand that by rocking or pivoting the right switch button 5062about the right switch axis RS-RS, the clinician can activate the rightcontact pad 5058 and by rocking the left switch button 5066, theclinician can activate the left contact pad 5059. The left and rightcontact pads 5058, 5059 may be in electrical communication with agenerator, e.g., via the connector module 5057. The generator may beprogrammed to modify the operation of the instrument 5000 in anysuitable manner in response to the activation of one of the switchbuttons 5062, 5066. For, example, in some forms one or both of theswitch buttons 5062, 5066 may be associated with an algorithm, such asthose described herein. For example, when the user selects one of thebuttons 5034, the generator may execute an algorithm, such as, forexample, one or more of algorithms 3021, 3021′, 3021″, 3120, 3170 any ofthe algorithms described with respect to FIGS. 15A-15C, 20-22, 57-60,etc. In some forms, the generator is configured to execute the samealgorithm in response to activation of either of the switch buttons5062, 5066, for example, so as to accommodate clinicians that are rightor left handed.

FIG. 109A, illustrates a switch assembly 5020′ that may include thefirst switch arrangement 5030 as well as a second switch arrangement5060′. In at least one form, the second switch arrangement 5060′includes a left switch button 5066′ that has a left pivot arm 5067protruding therefrom. The left switch button 5066′ may be pivotallymounted on pivot mounts 5007 or formations molded or otherwise formed inthe left handle housing 5004. The left switch button 5066′ may have abarrel-like shape or configuration and be selectively pivotable about aleft switch axis LS-LS that may be substantially transverse to the firstswitch axis FS-FS. The clinician may selectively pivot the left switchbutton 5066′ to bring an actuator portion 5069 of the left switch arm5067 into actuation contact with a corresponding left contact pad 5059supported within the handle assembly. In the illustrated arrangement,the second switch arrangement only includes the left switch button 5066′as described above. In alternative forms, the second switch arrangementmay only include a right switch button mounted on the right side of thehandle housing in the manner illustrated in FIG. 109A. Still other formsof the second switch arrangement may include both right and left switchbuttons mounted in the manner illustrated in FIG. 109A.

FIGS. 110 and 111 illustrate another form of a handle assembly 5100 thatis similar to the handle assembly 5000 described above, except that theright and left switch buttons 5162, 5166 do not pivot, but instead aresupported in their respective handle housing segments 5106, 5104 suchthat they may be depressed inwardly into contact with their respectiveright and left contacts (not shown). As with the handle assembly 5000described above, however, the right and left switch buttons 5162, 5166are located in the general thumb groove areas 5012, 5010, respectivelyin the manner described above to facilitate ease of operation when theclinician is gripping the pistol grip portion 5108.

FIG. 112 illustrates a portion of a left handle housing segment 5204 ofanother handle assembly 5200 wherein a left side button 5266 thereof maybe pivotally coupled to the switch frame 5250 as shown and be formedwith a switch post 5267 that is adapted to be pivoted into actuationcontact with the corresponding left contact pad 5059. The right buttonassembly (not shown) of the handle assembly 5200 may be similarlyconfigured. In alternative arrangements, the right and left buttons maybe pivotally coupled to their respective handle housing segments.

FIGS. 113 and 114 illustrate another form of a second switch arrangement5360 that may be employed for example in a handle assembly 5000described above in place of the second switch arrangement 5060. As canbe seen in FIGS. 113 and 114, the second switch arrangement 5360 mayinclude a left switch button 5366 that has a left switch arm 5370 thatextends laterally above and across a switch frame 5350 which issupported within the handle assembly as was discussed above. The leftswitch arm 5370 is configured to be pivotally coupled to a right portionor formation 5352 of the switch frame 5350 which is adjacent to a righthandle housing (not shown) of the handle assembly. The left switch arm5370 may be pinned for example to the right portion 5352 of the switchframe 5350 to define a right switch axis RS-RS about which the leftswitch arm may pivot. See FIG. 113. A left actuation pin or lug 5372extends downwardly from the left switch arm 5370 such that whenclinician rocks the left switch button 5366 in a manner described above,the left actuation pin 5372 is brought into actuation contact with thecorresponding left contact pad 5359 supported on the switch frame 5350.

Still referring to FIGS. 113 and 114, the second switch arrangement 5360may further include a right switch button 5362 that has a right switcharm 5380 that extends laterally above and across the left switch arm5370 to be pivotally coupled to a left portion or formation 5354 of theswitch frame 5350 which is adjacent to a left handle housing (not shown)of the handle assembly. The right switch arm 5380 may be pinned forexample to the left portion 5354 of the switch frame 5350 to define aleft switch axis LS-LS about which the right switch arm 5380 may pivot.See FIG. 113. A right actuation pin or lug 5382 extends downwardly fromthe right switch arm 5380 through a corresponding hole 5374 in the leftswitch arm 5370 such that when clinician rocks the right switch button5362 in a manner described above, the right actuation pin 5382 isbrought into actuation contact with the corresponding right contact pad5358 supported on the switch frame 5350. The right and left switch axesmay be substantially parallel to each other, but laterally displacedfrom each other. When employed in a handle assembly that includes afirst switch arrangement 5030, the right and left switch axes may eachbe substantially transverse to the first switch axis FS-FS of that firstswitch arrangement. Those or ordinary skill in the art will understandthat such switch arrangement facilitates longer pivot arms or lengthswhich also facilitate button motion that is substantially straight down.

FIG. 115 illustrates another form of second switch arrangement 5460 thatmay be employed for example in a handle assembly 5000 described above inplace of the second switch arrangement 5060. As can be seen in thatFigure, the left and right switch buttons 5566, 5562 are configured tobe pivotally coupled to a switch frame 5450 that is centrally disposedbetween the switch buttons 5566, 5562 and which defines a single switchaxis SA. When employed in a handle assembly that includes a first switcharrangement 5030, the switch axis SA may be substantially transverse tothe first switch axis FS-FS of that first switch arrangement. The switchframe 5450 may be rigidly supported within the handle housing assemblyand extend between the respective right and left handle housing segments(not shown).

In at least one form, the right switch button 5462 has a right link 5480extending therefrom which is pivotally coupled to the switch frame 5450.Likewise, the left switch button has a left link 5470 extendingtherefrom to be pivotally coupled to the switch frame 5460. The rightand left links 5480, 5470 may be pivoted to the switch frame 5450 by acommon pin (not shown) to define the switch axis SA about which thebuttons 5462 and 5466 may pivot. A right actuation pin or lug 5482extends inwardly from the right switch link 5480 such that whenclinician rocks or pivots the right switch button 5462 in a mannerdescribed above, the right actuation pin 5482 is brought into actuationcontact with the corresponding right contact pad 5458 supported on theswitch frame 5450. Likewise, a left actuation pin or lug 5472 extendsinwardly from the left switch link 5470 such that when the clinicianrocks or pivots the left switch button 5466 in a manner described above,the left actuation pin 5472 is brought into actuation contact with thecorresponding left contact pad 5459 on the switch frame 5450. Each ofthe switch arms 5470 and 5480 may be biased into unactuated positions bycorresponding springs or biasing arrangements (not shown) positioned,for example, between switch link 5470, 5480 and the frame 5450.

FIG. 116 illustrates another form of second switch arrangement 5560 thatmay be employed for example in a handle assembly 5000 described above inplace of the second switch arrangement 5060. As can be seen in thatFigure, the second switch arrangement 5560 employs a single secondswitch actuator 5561 that extends between the right handle housingportion 5006 and the left handle housing portion 5004 such that a rightend thereof forms the right switch button 5562 and the left end thereofforms the left switch button 5566. The second switch actuator 5561slidably extends through corresponding openings 5005 and 5007 in theleft and right handle housing segments 5004, 5006 such that the secondactuator 5561 may be selectively axially displaceable along a switchaxis SA-SA. When employed in a handle assembly 5000 that includes afirst switch arrangement 5030, the switch axis SA-SA may besubstantially parallel to the first switch FS-FS axis of that firstswitch arrangement.

A right biasing member 5590 and a left biasing member 5592 may bepositioned within the second switch actuator 5561 and configured tocooperate with a centrally disposed portion of the switch frame 5550 tokeep the second switch actuator 5561 centrally disposed in an unactuatedposition as shown in FIG. 116. A switch contact assembly 5557 may becentrally located between a right actuator member or protrusion 5563attached to or formed on the second actuator 5561 and a left actuatormember or protrusion 5565 formed on the second actuator 5561. The switchcontact assembly 5557 may, for example, have a right portion 5557R thatcorresponds to the right actuator 5563 and a left portion 5557L thatcorresponds to the left actuator member 5565. Thus, by depressing theright switch button 5562 inwardly, the second switch actuator 5561 willmove laterally in the left direction “LD” to bring the right actuator5563 into actuation contact with the right portion 5557R of the switchcontact assembly 5557. Likewise, by depressing the left switch button5566 inwardly, the second switch actuator 5561 will move laterally inthe right direction “RD” to bring the left actuator 5565 into actuationcontact with the left portion 5557L of the switch contact assembly 5557.

FIGS. 117-120 depict in somewhat diagrammatic form a switch assembly5620 that may be employed in connection with the various ultrasonichandle assemblies disclosed herein. In at least one form, the switchassembly 5620 includes a single button assembly 5632 that may belocated, for example, where the first button assembly 5032 is positionedin the handle assembly 5000 as was described in detail above. Forexample, the button assembly 5632 may include a button carriage arm 5633that has an actuator button 5634 formed thereon that may actuatable bythe clinician's index finger when the clinician is gripping the pistolportion of the corresponding handle assembly.

In at least one form, the button carriage arm 5633 may include a pair ofpivot pins 5637, 5639 that are movably received within an elongate slot5671 in a switch housing 5670 that is operably supported within thehandle housing. The button pivot pins 5637, 5639 facilitate axialmovement of the button carriage arm 5633 (FIG. 118) as well asrotational or pivotal movement of the button carriage arm 5633 relativeto the switch housing 5670 (FIGS. 119 and 120). As can be seen in FIGS.117-120, the elongate slot 5671 opens into a three-way actuator opening5673 that has a right end 5675 that corresponds to a right switch 5658,a left end 5677 that corresponds to a left switch 5659 and a central end5679 that corresponds to a central switch 5654. As can be seen in FIG.117, the button carriage arm 5633 may include a left switch actuatorportion 5690, a central switch actuator portion 5692 and a right switchactuator portion 5694. In addition, a right spring 5680 and a leftspring 5682 may be provided between the button carriage arm 5633 and thehandle housing 5002 to keep the button carriage arm 5633 in a centraland neutral position (FIG. 117) when it is unactuated.

Operation of the switch assembly 5620 may be understood from referenceto FIGS. 118-120. FIG. 118 illustrates actuation of the central switch5654 by depressing the actuator button 5634 inwardly as represented byarrow “D”. As the actuator button 5634 is depressed, the button carriagearm 5633 moves axially along or relative to the elongate slot 5671 inthe switch housing 5670 to bring the central switch actuator portion5692 into actuation contact with the central switch 5654. FIG. 119illustrates actuation of the right switch 5658 by pivoting the actuatorbutton 5634 in the direction represented by the arrow labeled “MIN”which brings the right switch actuator portion 5694 into actuationcontact with the right switch 5658. FIG. 120 illustrates actuation ofthe left switch 5659 by pivoting the actuator button 5634 in thedirection represented by the “MAX” arrow which brings the left switchactuator portion 5690 into actuation contact with the left switch 5659.The respective switches 5654, 5658, 5659 may be in electricalcommunication with a generator, for example, via a connector module5057, as described herein above. The generator may be programmed toperform any suitable action with respect to the instrument 500 inresponse to activation of one of the switches 5654, 5658, 5659. Forexample, in some forms, switches 5658 and 5659 perform a functionsimilar to that of the finger buttons 5034, 5036 described above. Forexample, activating one of the buttons 5658, 5659 may cause thegenerator to increase the power provided to the end effector whileactivating the other button 5658, 5659 may cause the generator todecrease the power provided to the end effector. Also, responsive to anyone or more of the buttons 5654, 5658, 5659, the generator may beconfigured to an algorithm, such as, for example, one or more ofalgorithms 3021, 3021′, 3021″, 3120, 3170 any of the algorithmsdescribed with respect to FIGS. 15A-15C, 20-22, 57-60, etc.

Different clinicians often have different techniques for usingultrasonic surgical instruments and systems as described herein. Forexample, some clinicians routinely activate an ultrasonic surgicalinstrument without fully closing the clamp arm against the blade.Although some clinicians believe that this technique improves systemperformance, in practice it often does not and has the potential todamage tissue, for example, by requiring longer transection times andsometimes causing transection and/or coagulation to be compromised.

In various forms, this and other problems may be addressed byconfiguring a surgical instrument with a closure switch indicating whenthe clamp arm is fully closed. The generator may be configured torefrain from activating the surgical instrument until or unless theclosure switch indicates that the clamp arm is fully closed. Referringnow to FIGS. 95 and 105, some forms of the closure switch are positionedin the handle 4122 (FIG. 95). For example, both FIGS. 95 and 105illustrate an optional closure switch 5900 positioned on an inside,proximal portion of the handle 4122 (FIG. 95) and one or more of thehandle housing segments 5004, 5006 (FIG. 105).

The switch 5900 may be positioned such that the trigger 4124 contactsthe switch 5900 at its proximal-most position. For example, the switch5900 may be positioned at an end of the stroke of the trigger 4124(e.g., in the direction of arrow 4121 a in FIG. 93). In this way, thetrigger 4124 may contact the switch 5900 when the trigger 4124 is pulledproximally to close the clamp arm against the blade. In various forms,the switch 5900 may be positioned anywhere were it will be activatedwhen the end effector is closed (e.g., the clamp arm is pivoted towardsthe blade). For example, the switch 5900 may be positioned distal of theyoke 4174 and/or reciprocating tubular actuating member 4138, so as tobe activated when one or the other of those components translatesdistally to close the end effector. The switch 5900 may be in electricalcommunication with the generator, such as generator 30, 50, 1002, forexample, via the connector module 5057 and/or 4200 and hand piece, asdescribed herein. In various forms, the generator is programmed not toactivate the surgical instrument unless the switch 5900 is alsoactivated. For example, if the generator receives an activation requestfrom one or more of the switches described herein, it may respond to theactivation request only if the switch 5900 is activated to indicate thatthe clamp arm is closed.

FIG. 121 illustrates a block diagram of a system 6000 depicting agenerator 6002 coupled to a medical instrument 6004 and a circuit 6006.The generator 6002 may be coupled directly to the instrument 6004 or maybe coupled through a cable 6008. The circuit 6006 may be connected tothe generator 6002 to receive an encoded transmission frame of bits froma signal conditioning circuit 2002 (e.g., from generator 1002 terminalsHS and SR (FIG. 19) via a pair of conductive elements HS/SR). In variousforms, the generator 6002 is functionally equivalent to the generator2002 and has been described in connection with FIG. 19. Therefore, forconciseness and clarity, the description of the generator 2002, 6002will not be repeated here. Nevertheless, it will be appreciated thatother generators may be employed in the system 6000. Also, although someaspects of the disclosed serial protocols may be described hereinbelowin connection with various circuits and systems, it will be appreciatedthat scope of the present disclosure is intended to encompass any andall methods for generating signals over a transmission frame inaccordance with the protocol timing diagrams disclosed in FIGS. 123-128.

The encoded transmission frame, which is described in detail hereinbelowin connection with FIGS. 123-127, is a repetitive, bidirectionalcommunication signal, where an encoded frame is repeatedly transmittedby the generator 6002. The frame comprises a series of bits thatsimultaneously encode input/output (I/O) information on a single bit bymodulating both the amplitude of the bit and the pulse width of the bit.The input bits are encoded such that information regarding the state ofthe circuit 6006 is communicated to the generator 6002 simultaneouslywith output bits encoded with information from the generator 6002regarding how to set the outputs of the circuit 6006 and, accordingly,the output states of the instrument 6004. In various forms describedherein, the generator 6002 modulates or sets the width of the pulses(time) to communicate information from the generator 6002 to the circuit6006 on how to set the outputs of the circuit 6006. In various formsdescribed herein, the circuit 6006 modulates or sets the height(amplitude) of the pulses to communicate information about the state ofthe circuit to the generator 6002. Furthermore, in one form, the circuit6006 may be parasitically powered from the bidirectional communicationsignal includes no other power source. In other forms, the circuit 6006may be powered from other power sources. In other forms, the circuit6006 may be both parasitically powered from the bidirectionalcommunication signal and other power sources.

The instrument 6004 comprises a circuit 6006, which may include at leastone switch that, in conjunction with the generator 6002, supportsactivation switch inputs and instrument EEPROMs. The circuit 6006 may beprovided within the instrument (as shown above with respect to datacircuits 2006, 2007. In some embodiments, the circuit 6006 may bepositioned on the hand piece, such as hand piece 1014 and may providethe generator with hand piece specific data such as, for example, acurrent set point, a gain, etc. The instruments 6004 provides variousI/O capabilities and may employ a plurality of switch inputs, analoginputs as well as discrete outputs, analog outputs. In order toimplement the functionality of the plurality of switch inputs andoutputs, the circuit 6006 communicates with the generator 6002 using anovel serial communication protocol, the timing diagrams of which areillustrated in connection with FIGS. 122-127. The circuit 6006 isconfigured to short circuit the HS-SR electrical conductive elementselectrically coupling the generator 6002 and the instrument 6004. Shortcircuiting the HS-SR lines enables the circuit 6006 to set thetransmission frame start and stop pulses, which also may be referred toas start/stop bits. In addition to setting the frame length, shortcircuiting the HS-SR lines enables the generator 6002 to conduct a loopcalibration where the generator 6002 measures the loop resistance foreach frame being transmitted.

Forms of the generator 6002 may enable communication with one or morecircuits 6006 contained in the instrument 6004. In certain forms, thecircuit 6006 may generally be any circuit for transmitting and/orreceiving data. In one form, for example, the circuit 6006 may storeinformation pertaining to the particular surgical instrument 6004 withwhich it is associated. Such information may include, for example, amodel number, a serial number, a number of operations in which thesurgical instrument has been used, and/or any other type of information.Additionally or alternatively, any type of information may becommunicated to circuit 6006 for storage therein. Such information maycomprise, for example, an updated number of operations in which theinstrument 6004 has been used and/or dates and/or times of its usage. Incertain forms, the circuit 6006 may transmit data acquired by one ormore sensors (e.g., an instrument-based temperature sensor). In certainforms, the circuit 6006 may receive data from the generator 6002 andprovide an indication to a user (e.g., an LED, power switch information,and audible and/or visible indication) based on the received data.

In certain forms, the circuit 6006 may be configured such thatcommunication between instrument 6004 and the generator 6002 can beeffected without the need to provide additional conductors for thispurpose (e.g., dedicated conductors of a cable connecting a hand pieceto the generator 6002). In one form, for example, information may becommunicated to and from the circuit using a 1-wire bus communicationscheme implemented on existing cabling, such as one of the conductorsused to transmit interrogation signals from the signal conditioningcircuit to the circuit 6006 in the instrument. In this way, designchanges or modifications to the instrument 6004 that might otherwise benecessary are minimized or reduced. Moreover, because different types ofcommunications can be implemented over a common physical channel (eitherwith or without frequency-band separation), the presence of the circuit6004 may be “invisible” to the generators that do not have the requisitedata reading functionality, thus enabling backward compatibility of theinstrument 6004.

The generator 6002 may exchange information with the circuit 6006 thatis specific to a surgical device integral with, or configured for usewith, the cable 6008 and may comprise, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. Information may also becommunicated from the generator 6002 to the circuit 6006 for storagetherein. In one form, the circuit 6006 need not be located on or in theinstrument 6004, but may be disposed in an adaptor for interfacing aspecific instrument 6004 type or model with the generator 6002.

FIG. 122 illustrates a block diagram of the circuit 6006 within theinstrument 6004. The circuit 6006 may be connected to the generator toreceive an interrogation signal via a pair conductive pair of conductiveelements 6010, 6012. The circuit 6006 may comprise multiple branches. Afirst branch comprises a controller 6014, a second branch comprises adata circuit 6016, and additional branches may comprise additional datacircuits 6018 or other circuits, sensors, switches, indicators (audible,tactile, visual). The controller 6014, the data circuits 6018, and/orother circuits may be parasitically powered by the energy in the framebits. In other forms, the controller 6014, the data circuits 6018,and/or other circuits may be powered from other power sources. In otherforms, the controller 6014, the data circuits 6018, and/or othercircuits may be both parasitically powered from the bidirectionalcommunication signal and other power sources.

The controller 6014 may be an application specific integrated circuit(ASIC), a microcontroller comprising a processor and memory, a digitalsignal processing circuit, a programmable logic device, fieldprogrammable gate array, discrete circuit, and the like. The controllercomprises a plurality of inputs S₀ to S_(n), where n is a suitableinteger. As illustrated in FIG. 122, the plurality of inputs S₀ to S_(n)are coupled to a plurality of switches SW₀ to SW_(n), where n is anysuitable integer. The switches SW₀ to SW_(n) provide inputs to thecontroller 6014 to control functions associated with the instruments6004. The controller 6014 communicates the states of the switches SW₀ toSW_(n) to the generator 6002 via a serial protocol in accordance withthe present disclosure.

The controller 6014 also comprises a plurality of outputs O₀ to O_(m),where m is any suitable integer, and may be the same as n. The outputsO₀ to O_(m) are driven by the controller 6014 to control functionsassociated with the instrument 6004 in accordance with informationcommunicated by the generator 6002.

In various forms, the circuit 6006 also may comprise one or more datacircuits 6016, 6018 that communicate over a 1-wire protocol. In certainforms, the data circuits 6016, 6018 include storage elements that may bea single-wire bus device (e.g., a single-wire protocol EEPROM), or othersingle-wire protocol or local interconnect network (LIN) protocoldevice. In one form, for example, the data storage element 302 maycomprise a single wire EEPROM. The data storage element is one exampleof a circuit element that may be contained in the data circuits 6016,6018. The data circuit may additionally or alternatively comprise one ormore other circuit elements or components capable of transmitting orreceiving data. Such circuit elements or components may be configuredto, for example, transmit data acquired by one or more sensors (e.g., aninstrument-based temperature sensor) and/or receive data from thegenerator 6002 and provide an indication to a user (e.g., an LEDindication or other visible indication) based on the received data.

During operation, the generator 6002 and the circuit 6006 communicateover a robust, flexible, highly noise-immune communications protocolaccording to the present disclosure. The protocol is used over the twoinstrument conductive elements 6010, 6012 (HS, HSR) to allow thegenerator 6002 to communicate up to 8 or more discrete inputs andoutputs to the instrument 6004, while coexisting on the same lines asthe 1-Wire EEPROM (e.g., data circuits 6016, 6018) communications, andmaintaining backward compatibility with existing legacy circuits. Theprotocol comprises a frame that is repeatedly transmitted. The framecomprises overhead pulses (bits) such as start/stop and header pulsesand simultaneously encoded information pulses (bits) that encode bothinput and output information into a single pulse (bit) by modulatingboth the amplitude and width (pulse duration) of each information pulse.

One form of such a protocol is illustrated in connection with FIGS. 123and 124, where FIG. 123 shows a timing diagram 6020 of current pulses ina frame of a serial protocol at the generator 6002 output and FIG. 124shows a timing diagram 6022 of voltage pulses in a frame of the serialprotocol at the circuit 6014 output. Turning first to FIG. 123 whosedescription should be read in conjunction with FIG. 122, the timingdiagram 6020 shows an output signal from the generator 6002 to thecontroller 6014 in the form of current pulses. The current limit (rails)may be selected in accordance with the specific generator6002/instrument 6006 combination. In one form, for example, the currentrails are +15 mA and −15 mA. A frame begins and ends on the rising edges6023 a, 6023 b of start/stop pulses 6024 a, 6024 b generated by thecontroller 6014 by applying a short circuit across the rails HS-SR. Theframe begins on the rising edge 6023 a of the start pulse 6024 a andends on the rising edge 6023 b of the stop pulse 6024 b. The currentsignal pulses swing from the negative rail −I to the positive rail +Ithough a zero crossover during the transmission of the start pulse 6024a from the generator 6002 to the controller 6014. After the start pulse6024 is generated, the header pulses 6026, 6028 and encoded I/Oinformation pulses 6025 are transmitted. After the last encodedinformation pulse 6025 is transmitted the rising edge 6023 b of the stoppulse 6024 b signals the end of the current frame. The next frame isthen initiated and the process repeats. In one aspect, the frame bitsother than the start/stop pulses 6024 a, 6024 b swing from 0 to thenegative rail −I. In other aspects, some of the frame bits following thestart pulse 6024 a swing between the positive and negative rails +I, −I.The latter aspect is discussed hereinbelow in connection with FIG. 128.

The frame information pulses are simultaneously encoded both in regardsto width and amplitude. The width of the start/stop pulses 6204 a, 6024b is t_(o). The current pulses following the start pulse 6024 a areheader pulses represent header pulses 6026, 6028 and also have a pulsewidth t₀. In the context of encoding output pulses carrying informationfrom the generator 6002 to the instrument 6004, the information pulses6025 are encode as a logic “1” output pulse 6030 by increasing the pulseto width to t₁ whereas a logic “0” output pulse 6032 may have the samepulse width t₀ as the start pulse 6024 the header pulses 6026, 6028.Output logic “1” maps to the output active state, where the instrument6004 is drawing power from the generator 6002. As previously discussed,a frame is initiated with the rising edge 6023 a of the start currentpulse 6024 by short circuiting the first conductive element 6010 (HS) tothe second conductive element 6012 (SR), which are the power and signallines connecting the generator 6002 with the instrument 6004.

FIG. 124 shows the timing diagram 6022 of voltage pulses +/−V through azero crossover. The timing diagram 6022 shows I/O information pulsessimultaneously encoded with input information from the controller 6014to the generator 6002 (inputs) and output information from the generator6002 to the controller 6014 (output). Besides the start pulse 6034 a theserial communication occurs between zero and the negative side of thesignal. As shown, a logic “1” input voltage signal −V₁ is negative butmore positive than a logic “0” input voltage signal −V₀. Input logic “1”maps to a switch (SW₀-SW_(n)) closed state.

With reference now to the timing diagrams 6020, 6022 shown in FIGS. 123,124 in conjunction with the circuit 6006 shown in FIG. 122, a frame isinitiated at the rising edge 6023 a of the a start pulse 6034 a and endsat the rising edge of the stop pulse 6023 b. In between, the framecomprises two header pulses 6040, 6042 transmitted after the start pulse6024 a and a plurality of simultaneously encoded I/O information pulses6044. In one form, bits 6048 between the header pulses 6042, 6042 andinformation pulses 6044 return to zero and have a pulse width of t₀. Inother forms, as described hereinbelow, in connection with FIG. 128, bitsbetween the header pulses 6042, 6042 and information pulses 6044 returnto either one of the positive or negative rails in alternating fashion.It will be appreciated that one benefit of such a configuration isexploitation of additional parasitic power from the frame signals topower the circuit 6066.

The information pulses 6044 are encoded to carry information about bothinput and output. Accordingly, each information pulse 6044 defines afirst logic state associated with an input from the instrument 6004 tothe generator 6002 as well as a second logic state associated with anoutput from the generator 6002 to the instrument 6002. The simultaneousencoding of I/O signals is discussed in more detail in connection withFIGS. 125A-D, where the four logic states of an encoded I/O bit aredepicted separately for clarity of disclosure.

With reference back to FIG. 124, the header pulse 6040 represents aninput logic “0” and header pulse 6042 represents an input logic “1”. Theheader pulses 6040, 6042 can be used by the generator 6002 for presencedetection and to identify the circuit 6006 type. The generator 6002 mayuse specific ADC values read for either or both of the header pulses6040, 6042, or start bit 6084 to calibrate the ADC ranges for the inputpulses within the current frame. The generator 6002 will determine thenumber of inputs and outputs used by the specific instrument 6004 byreading parameters from the EEPROM 6016, 6018.

The number of I/O pulses per frame may be the greater of the number ofused inputs or outputs for a given instrument 6004 or may be a fixednumber. Although the maximum number of both inputs and outputs is apredetermined number, for example 8 (16 total), unused inputs andoutputs for a given instrument 6004 may or may not be implemented orpinned out. Unused inputs (if there are more outputs than inputs) can beset by the circuit 6006 to logic “0”. Unused outputs can be set by thegenerator 6002 to logic state “0” or “1” as appropriate, to optimizeeither polling speed or energy transfer to the circuit 6006. The circuit6006 will store energy from the negative pulses to power both its owncircuitry, and any output devices (e.g., LEDs, switches, power switchesincluding transistors, feedback devices, e.g., audio, visual, tactile).EEPROM 6016, 6018 communications will occur on the positive voltage sideof the signal.

Turning to the legend 6054 below the timing diagram 6022, it can be seenthat each information pulse 6044 has two possible input logic states(input logic “1” and input logic “0”) indicated by two negative voltagelevels −V₁, −V₀, and two possible output logic states (output logic “1”and output logic “0”) indicated by two pulse width t₁, t₀. Accordingly,if a switch (SW₀-SW_(n)) closure occurs, the next information pulsedrops to the input logic “1” state −V₁ and if a switch (SW₀-SW_(n))remains open the next information pulse drops to the input logic “0”state −V₀. At the same time interval, if the instrument 6004 is drawingpower from the generator 6002, the output logic “1” pulse width is t₁,and if instrument 6004 is not drawing power from the generator 6002, theoutput logic “0” pulse width is t₀.

As indicated in the timing diagram 6022, the pulse width of the resetpulse 6034, the header pulses 6040, 6042, the output logic “0” pulses,and the return to zero pulses 6048 each have pulse widths of t₀. Onlythe output logic “1” pulses have a pulse width of t₁, where t₀<t₁. Itwill be appreciated that the specific voltage levels and pulse widthsillustrated herein may be selected otherwise such that −V₁<−V₂ andt₀>t₁. Also, the reset pulse 6034, the header pulses 6040, 6042, theoutput logic “0” pulses, and the return to zero pulses 6048 each mayhave different pulse widths.

As illustrated in FIGS. 125A-D, an information pulse 6056 may be encodedin two of four I/O logic states during communication between thegenerator 6002 and the instrument 6004, e.g., the circuit 6006. In FIG.125A, for example, the information pulse 6056A represents an input logic“0” and an output logic “0” because the logic voltage level is −V₀ andthe logic current pulse width is t₀. In FIG. 125B, for example, theinformation pulse 6056B represents an input logic “1” and an outputlogic “0” because the logic voltage level is −V₁ and the logic currentpulse width is t₀. In FIG. 125C, for example, the information pulse6056C represents an input logic “0” and an output logic “1” because thelogic voltage level is −V₀ and the logic current pulse width is t₁. InFIG. 125D, for example, the information pulse 6056D represents an inputlogic “1” and an output logic “1” because the logic voltage level is −V₁and the logic current pulse width is t₁.

FIG. 126 illustrates one example timing diagram 6064 of a serialprotocol. As shown in FIG. 126, and with reference also to FIG. 122, thetiming diagram 6064 represents a protocol communication signalcomprising three inputs and no outputs. The inputs, referenced as S₀,S₁, and S₂ in FIG. 22, are coupled into controller 6014 portion of thecircuit 6006. The three inputs may be associated with the state of theswitches SW₀, SW₁, SW₂ coupled to the controller 6014, or may beassociated with other types of inputs. The controller 6014 modulates theamplitude of a corresponding encoded bit to −V₀ or −V₁ based on thestate (open or closed) of the switches SW₀, SW₁, SW₂. The frame in thisexample comprises a start pulse 6034 a, two header pulses 6040, 6042,and three information pulses 6058, 6060, 6062 corresponding with thestates of the switches SW₀, SW₁, SW₂, for a total of six pulses. Theframe ends on the rising edge 6023 b of the stop pulse 6034 b.

As shown in FIG. 126, the first and second information pulses 6058, 6060are input logic “0” indicating that the input switches SW₀, SW₁, SW₂ areopen and the third information pulse is input logic “1” indicating thatthe switch SW₂ is closed. Since there are no outputs, there are nooutput pulses being encoded, thus the frame consists of six pulses,three overhead pulses (e.g., reset and header pulses 6034, 6040, 6042)and three information pulses 6058, 6060, 6062. The frame is repeatedlytransmitted to inform the generator 6002 of the state of the inputswitches SW₀, SW₁, SW₂ at the instrument 6004. When a change occurs inthe state of a switch SW₀, SW₁, SW₂, the bit associated with that switchis automatically encoded and the frame repeats.

FIG. 127 illustrates one example timing diagram 6068 of a serialprotocol. As shown in FIG. 127, and with reference also to FIG. 122, thetiming diagram 6068 represents a protocol communication signalcomprising four inputs and two outputs. The inputs, referenced as S₀,S₁, S₂ and S₃ in FIG. 22, are coupled into controller 6014 portion ofthe circuit 6006. The outputs are associated with O₀ and O₁ of thecontroller 6014. The four inputs may be associated with the state of theswitches SW₀, SW₁, SW₂, SW₃ coupled to the controller 6014, or may beassociated with other types of inputs. The outputs O₀ and O₁ are used tocontrol various functions of the instrument 6004 such as, for example,driving audible, visual, tactile feedback, power control, among otherfunctions. The controller 6014 modulates the pulse height (amplitude) ofcorresponding encoded bits to −V₀ or −V₁ based on the state (open orclosed) of the switches SW₀, SW₁, SW₂, SW₃. The generator 6002 modulatesthe pulse width (time) of the encoded bit based on the output controlinformation that the generator 6002 wishes to communicate to thecontroller 6014. The frame in this example comprises a start pulse 6034a, two header pulses 6040, 6042, and four information pulses 6058, 6060,6062 corresponding with the states of the switches SW₀, SW₁, SW₂, SW₃,for a total of seven pulses. The frame ends on the rising edge 6023 b ofthe stop pulse 6034 b.

As shown in FIG. 127, the controller 6014 has encoded the firstinformation bit 6070 with both input and output information. Thus, thevoltage and pulse width of the first information bit 6070 are modulatedto encode the output as logic “0” and the input as logic “1”. Likewise,the controller 6014 has encoded the second information bit 6072 withboth input and output information. Thus, the voltage and pulse width ofthe second information bit 6072 are modulated to encode the output aslogic “1” and the input as logic “0”. Since in this example there arefour inputs and only two outputs, the third and fourth bits 6074, 6076are encoded with input information only, where the third bit 6074 isencoded as input logic “1” and the fourth bit is encoded as input logic“0”. The frame is repeatedly transmitted to inform the generator 6002 ofthe state of the input switches SW₀, SW₁, SW₂, SW₃ at the instrument6004 and the outputs O₀ and O₁ are driven by the controller 6014. When achange occurs in the state of a switch SW₀, SW₁, SW₂, SW₃, or thegenerator 6002 wants to control one of the two outputs O₀ and O₁, thebits associated therewith are automatically encoded and the framerepeats.

FIG. 128 illustrates example timing diagrams 6080, 6083 of a serialprotocol. With reference now to FIGS. 128 and 122, the top waveform is acurrent timing diagram 6080 as output by the generator 6002. The currentsignal swings from +I to −I crossing at zero. This timing diagram 6080provides power to the circuit 6014 continuously except during the startbits 6084, input logic “1” transmission 6086, and stop bit 6102 “noerror” condition. The bottom waveform 6082 is a voltage timing diagramat the circuit 6014. A header bit 6104 starts the frame followed by onestart bit 6084. The 12 input bits and 12 output bits are simultaneouslyencoded over a single frame as discussed above, where the input logicbits are encoded by modulating the pulse amplitude and output logic bitsare encoded by modulating the pulse width. The 12 information bits arethen transmitted to encode 12 inputs and 12 outputs. As shown, input #16086 is encoded as logic “1” and output #1 6090 is encoded as logic “0”.Input #2 6088 is encoded as logic “1” and output #2 6092 is encoded aslogic “1”. Input #3 6094 is encoded as logic “0” and output #3 6092 isencoded as logic “1”. The last bit represents input #12 6098 is encodedas logic “0” and output #12 is encoded as logic “0”. As indicated, everyother bit 6106 returns to the positive supply rail, which providesadditional parasitic power for the instrument 6004 circuit 6006.

While various details have been set forth in the foregoing description,it will be appreciated that the various aspects of the serialcommunication protocol for medical device may be practiced without thesespecific details. For example, for conciseness and clarity selectedaspects have been shown in block diagram form rather than in detail.Some portions of the detailed descriptions provided herein may bepresented in terms of instructions that operate on data that is storedin a computer memory. Such descriptions and representations are used bythose skilled in the art to describe and convey the substance of theirwork to others skilled in the art. In general, an algorithm refers to aself-consistent sequence of steps leading to a desired result, where a“step” refers to a manipulation of physical quantities which may, thoughneed not necessarily, take the form of electrical or magnetic signalscapable of being stored, transferred, combined, compared, and otherwisemanipulated. It is common usage to refer to these signals as bits,values, elements, symbols, characters, terms, numbers, or the like.These and similar terms may be associated with the appropriate physicalquantities and are merely convenient labels applied to these quantities.

Unless specifically stated otherwise as apparent from the foregoingdiscussion, it is appreciated that, throughout the foregoingdescription, discussions using terms such as “processing” or “computing”or “calculating” or “determining” or “displaying” or the like, refer tothe action and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

It is worthy to note that any reference to “one aspect,” “an aspect,”“one form,” or “an form” means that a particular feature, structure, orcharacteristic described in connection with the aspect is included in atleast one aspect. Thus, appearances of the phrases “in one aspect,” “inan aspect,” “in one form,” or “in an form” in various places throughoutthe specification are not necessarily all referring to the same aspect.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more aspects.

Some aspects may be described using the expression “coupled” and“connected” along with their derivatives. It should be understood thatthese terms are not intended as synonyms for each other. For example,some aspects may be described using the term “connected” to indicatethat two or more elements are in direct physical or electrical contactwith each other. In another example, some aspects may be described usingthe term “coupled” to indicate that two or more elements are in directphysical or electrical contact. The term “coupled,” however, also maymean that two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other.

It is worthy to note that any reference to “one aspect,” “an aspect,”“one form,” or “an form” means that a particular feature, structure, orcharacteristic described in connection with the aspect is included in atleast one aspect. Thus, appearances of the phrases “in one aspect,” “inan aspect,” “in one form,” or “in an form” in various places throughoutthe specification are not necessarily all referring to the same aspect.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more aspects.

Although various forms have been described herein, many modifications,variations, substitutions, changes, and equivalents to those forms maybe implemented and will occur to those skilled in the art. Also, wherematerials are disclosed for certain components, other materials may beused. It is therefore to be understood that the foregoing descriptionand the appended claims are intended to cover all such modifications andvariations as falling within the scope of the disclosed forms. Thefollowing claims are intended to cover all such modification andvariations.

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). Those having skill in the art will recognize that thesubject matter described herein may be implemented in an analog ordigital fashion or some combination thereof.

The foregoing detailed description has set forth various forms of thedevices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In one form, severalportions of the subject matter described herein may be implemented viaApplication Specific Integrated Circuits (ASICs), Field ProgrammableGate Arrays (FPGAs), digital signal processors (DSPs), or otherintegrated formats. However, those skilled in the art will recognizethat some aspects of the forms disclosed herein, in whole or in part,can be equivalently implemented in integrated circuits, as one or morecomputer programs running on one or more computers (e.g., as one or moreprograms running on one or more computer systems), as one or moreprograms running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of skill in the art in light of this disclosure.In addition, those skilled in the art will appreciate that themechanisms of the subject matter described herein are capable of beingdistributed as a program product in a variety of forms, and that anillustrative form of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude, but are not limited to, the following: a recordable type mediumsuch as a floppy disk, a hard disk drive, a Compact Disc (CD), a DigitalVideo Disk (DVD), a digital tape, a computer memory, etc.; and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link (e.g., transmitter,receiver, transmission logic, reception logic, etc.), etc.).

All of the above-mentioned U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications, non-patent publications referred to in this specificationand/or listed in any Application Data Sheet, or any other disclosurematerial are incorporated herein by reference, to the extent notinconsistent herewith. As such, and to the extent necessary, thedisclosure as explicitly set forth herein supersedes any conflictingmaterial incorporated herein by reference. Any material, or portionthereof, that is said to be incorporated by reference herein, but whichconflicts with existing definitions, statements, or other disclosurematerial set forth herein will only be incorporated to the extent thatno conflict arises between that incorporated material and the existingdisclosure material.

One skilled in the art will recognize that the herein describedcomponents (e.g., operations), devices, objects, and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are contemplated.Consequently, as used herein, the specific exemplars set forth and theaccompanying discussion are intended to be representative of their moregeneral classes. In general, use of any specific exemplar is intended tobe representative of its class, and the non-inclusion of specificcomponents (e.g., operations), devices, and objects should not be takenlimiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable,” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents, and/or wirelessly interactable, and/or wirelesslyinteracting components, and/or logically interacting, and/or logicallyinteractable components.

In some instances, one or more components may be referred to herein as“configured to,” “configurable to,” “operable/operative to,”“adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Thoseskilled in the art will recognize that “configured to” can generallyencompass active-state components and/or inactive-state componentsand/or standby-state components, unless context requires otherwise.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to claims containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that typically a disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms unless context dictates otherwise. For example, the phrase “Aor B” will be typically understood to include the possibilities of “A”or “B” or “A and B.”

With respect to the appended claims, those skilled in the art willappreciate that recited operations therein may generally be performed inany order. Also, although various operational flows are presented in asequence(s), it should be understood that the various operations may beperformed in other orders than those which are illustrated, or may beperformed concurrently. Examples of such alternate orderings may includeoverlapping, interleaved, interrupted, reordered, incremental,preparatory, supplemental, simultaneous, reverse, or other variantorderings, unless context dictates otherwise. Furthermore, terms like“responsive to,” “related to,” or other past-tense adjectives aregenerally not intended to exclude such variants, unless context dictatesotherwise.

In certain cases, use of a system or method may occur in a territoryeven if components are located outside the territory. For example, in adistributed computing context, use of a distributed computing system mayoccur in a territory even though parts of the system may be locatedoutside of the territory (e.g., relay, server, processor, signal-bearingmedium, transmitting computer, receiving computer, etc. located outsidethe territory).

A sale of a system or method may likewise occur in a territory even ifcomponents of the system or method are located and/or used outside theterritory. Further, implementation of at least part of a system forperforming a method in one territory does not preclude use of the systemin another territory.

Although various forms have been described herein, many modifications,variations, substitutions, changes, and equivalents to those forms maybe implemented and will occur to those skilled in the art. Also, wherematerials are disclosed for certain components, other materials may beused. It is therefore to be understood that the foregoing descriptionand the appended claims are intended to cover all such modifications andvariations as falling within the scope of the disclosed forms. Thefollowing claims are intended to cover all such modification andvariations.

In summary, numerous benefits have been described which result fromemploying the concepts described herein. The foregoing description ofthe one or more forms has been presented for purposes of illustrationand description. It is not intended to be exhaustive or limiting to theprecise form disclosed. Modifications or variations are possible inlight of the above teachings. The one or more forms were chosen anddescribed in order to illustrate principles and practical application tothereby enable one of ordinary skill in the art to utilize the variousforms and with various modifications as are suited to the particular usecontemplated. It is intended that the claims submitted herewith definethe overall scope.

EXAMPLES

In one general aspect, a surgical instrument assembly embodying theprinciples of the described forms is configured to permit selectivedissection, cutting, coagulation, and clamping of tissue during surgicalprocedures. A generator may generate at least one electrical signal,which may be monitored against a first set of logic conditions. When thefirst set of logic conditions is met, a first response of the generatormay be triggered.

In certain forms, ultrasonic impedance of the surgical instrument ismonitored. When the ultrasonic impedance of the surgical instrumentexceeds a threshold impedance, a resonant frequency of the at least oneelectrical signal may be stored as a baseline frequency. Also, the firstresponse of the generator may be triggered when either the first set oflogic conditions is met or the resonant frequency of the at least oneelectrical signal differs from the baseline frequency by a baselinedeviation threshold.

In certain forms, load events at an end effector of the surgicalinstrument may be monitored. The first response of the generator may betriggered when the first set of logic conditions is met and a load eventis detected.

In accordance with one general form, there is provided a switch assemblyfor an ultrasonic surgical instrument that includes a handle housingthat is configured to be supported in one hand. In at least one form,the switch assembly comprises a first switch arrangement that isoperably supported on a forward portion of the handle housing and isselectively movable relative to at least one first switch contact. Theswitch assembly further comprises a second switch arrangement that maycomprise at least one of a right switch button and a left switch button.The right switch button may be movably supported on a right side of thehandle housing and be selectively movable relative to at least one rightswitch contact supported by the handle housing. The left switch buttonmay be movably supported on a left side of the handle housing and beselectively movable relative to at least one left switch contactsupported by the handle housing. The first and second switcharrangements may be configured to be selectively operated by a singlehand supporting the handle housing.

In accordance with at least one other general form, there is provided anultrasonic surgical instrument. In at least one form, the ultrasonicsurgical instrument comprises a generator for generating ultrasonicsignals and a handle assembly that includes a handle housing that isconfigured to be operably supported in one hand. The instrument mayfurther comprise a switch assembly that includes a first switcharrangement that is operably supported on a forward portion of thehandle housing and is selectively movable relative to at least one firstswitch contact that communicates with the generator. The switch assemblymay further include a second switch arrangement that comprises at leastone of a right switch button and a left switch button. The right switchbutton may be movably supported on a right side of the handle housingand be selectively movable relative to at least one right switch contactthat is supported by the handle housing. The at least one right switchcontact may communicate with the generator. The left switch button maybe movably supported on a left side of the handle housing and beselectively movable relative to at least one left switch contact that issupported by the handle housing and may operably communicate with thegenerator. The first and second switch arrangements may be configured tobe selectively operated by a single hand supporting the handle housing.

In accordance with still another general form, there is provided aswitch assembly for an ultrasonic surgical instrument that includes ahandle housing that is configured to be supported in one hand. In atleast one form, the switch assembly comprises a button assembly that ismovably supported by the handle housing for selective axial and pivotaltravel relative to a right switch contact, a central switch contact anda left switch contact such that axial movement of the button assembly ina first direction causes the button assembly to actuate the centralswitch contact and pivotal movement of the button assembly in a firstpivotal direction causes the button assembly to actuate the left switchcontact and pivotal movement of the button assembly in a second pivotaldirection causes the button assembly to actuate the right switchcontact.

According to various forms, the connector module may be a modularcomponent that may be provided as an accessory with the ultrasonicsurgical instrument or components thereof but not attached thereto ormay be used to repair, replace, or retrofit ultrasonic surgicalinstruments. In certain forms, however, the connector module may beassociated with the handle assembly or the ultrasonic transducer. In oneform, the connector module may comprise an assembly that may be easilyremoved and/or replaced by a user. The connector module may alsocomprise removable features allowing the user to, for example, removeand/or replace rotation couplings, switch conductors, or links.Accordingly, in certain forms, one or more connector modules may beincluded in a kit. The kit may comprise various rotation couplingsconfigured for adaptable use with one or more ultrasonic transducers orhand pieces. The kit may include connector modules, rotation couplings,or housings comprising various configurations of user interfaces thatmay require one, two, or more conductive paths.

In one aspect, the present disclosure is directed to an ultrasonicsurgical instrument. The ultrasonic instrument may comprise an endeffector, a waveguide extending proximally from the end effector along alongitudinal axis, and a connector module for receiving an ultrasonichand piece. The connector module may comprise a housing defining aspindle extending along the longitudinal axis, a coupling positioned onthe spindle and rotatable relative to the housing, a first conductormechanically coupled to the housing and extending at least partiallyaround the longitudinal axis, and a first link rotatable about thelongitudinal axis relative to the first conductor between a firstposition and a second position. The first link may comprise a firstcontact positioned to electrically contact the first conductor when thefirst link is in the first position and the second position and a secondcontact electrically coupled to the first contact and positioned toelectrically contact the ultrasonic hand piece when the first link is inthe first position and the second position.

In one aspect, the first and second conductors each comprise aconductive lead configured to electrically couple to a user interfaceconfigured for receiving power control signals from a user. Theultrasonic hand piece may be adapted to electrically couple to agenerator and rotationally couple to the first and second links whenreceived by the connector module. The connector module may be configuredto electrically couple the user interface circuit and the generator viathe ultrasonic hand piece when the first and second links are inrespective first and second positions. In one aspect, the user interfacecomprises a toggle switch operatively coupled to a handle assembly andthe connector module is secured to the handle assembly. The ultrasonichand piece may be rotatable relative to the handle assembly whenreceived by the connector module. In one aspect, the housingelectrically isolates the first and second conductors with respect toeach other.

Various aspects of the subject matter described herein are directed toan apparatus, comprising a circuit configured to transmit a signal as aserial protocol over a pair of electrical conductors. The serialprotocol may be defined as a series of pulses distributed over at leastone transmission frame. At least one pulse in the transmission frame issimultaneously encoded by modulating an amplitude of the pulse torepresent one of two first logic states and modulating a width of thepulse to represent one of two second logic states.

Various aspects of the subject matter described herein are directed toan instrument, comprising a circuit configured to transmit a signal as aserial protocol over a pair of electrical conductors. The serialprotocol may be defined as a series of pulses distributed over at leastone transmission frame. At least one pulse in the transmission frame maybe simultaneously encoded by modulating an amplitude of the pulse torepresent one of two first logic states and modulating a width of thepulse to represent one of two second logic states. The instrument mayalso comprise an output device coupled to an output of the circuit; andan input device coupled to an input of the circuit.

Various aspects of the subject matter described herein are directed to agenerator, comprising a conditioning circuit configured to communicateto an instrument over a two wire interface. The generator may comprisesa control circuit configured to transmit a signal as a serial protocolover a pair of electrical conductors. The serial protocol may be definedas a series of pulses distributed over at least one transmission frame.At least one pulse in the transmission frame is simultaneously encodedby modulating an amplitude of the pulse to represent one of two firstlogic states and modulating a width of the pulse to represent one of twosecond logic states. The generator may also comprise an energy circuitconfigured to drive the instrument.

Various aspects are directed to methods of driving an end effectorcoupled to an ultrasonic drive system of an ultrasonic surgicalinstrument. A trigger signal may be received. In response to the triggersignal, a first drive signal may be provided to the ultrasonic drivesystem to drive the end effector at a first power level. The first drivesignal may be maintained for a first period. At the end of the firstperiod a second drive signal may be provided to the ultrasonic drivesystem to drive the end effector at a second power level less than thefirst power level.

In another aspect, after receiving a trigger signal, a surgical systemgenerates feedback indicating that the ultrasonic surgical instrument isactivated while maintaining the ultrasonic instrument in a deactivatedstate. At an end of the threshold time period, the ultrasonic surgicalinstrument is activated by providing a drive signal to the ultrasonicdrive system to drive the end effector.

In another aspect, the ultrasonic surgical instrument is activated bygenerating a drive signal provided to the ultrasonic drive system todrive the end effector. A plurality of input variables may be applied toa multi-variable model to generate a multi-variable model output, wherethe multi-variable model output corresponds to an effect of theultrasonic instrument on tissue. The plurality of input variables maycomprise at least one variable describing the drive signal and at leastone variable describing a property of the ultrasonic surgicalinstrument. When the multi-variable model output reaches a thresholdvalue, feedback may be generated indicating a corresponding state of atleast one of the ultrasonic surgical instrument and tissue acted upon bythe ultrasonic surgical instrument.

In another aspect, in response to a trigger signal, a first drive signalat a first power level is provided to the ultrasonic drive system todrive the end effector. The first drive signal is maintained at thefirst level for a first period. A second drive signal is provided to theultrasonic drive system to drive the end effector at a second powerlevel less than the first power level. A plurality of input variablesmay be applied to a multi-variable model to generate a multi-variablemodel output. The multi-variable model output may correspond to aneffect of the ultrasonic instrument on tissue, and the plurality ofvariables may comprise at least one variable describing the drive signaland at least one variable describing a property of the ultrasonicsurgical instrument. After the multi-variable model output exceeds athreshold value for a threshold time period, a first response may betriggered.

While several forms have been illustrated and described, it is not theintention of the applicant to restrict or limit the scope of theappended claims to such detail. Numerous variations, changes, andsubstitutions will occur to those skilled in the art without departingfrom the scope of the invention. Moreover, the structure of each elementassociated with the described forms can be alternatively described as ameans for providing the function performed by the element. Accordingly,it is intended that the described forms be limited only by the scope ofthe appended claims.

Reference throughout the specification to “various forms,” “some forms,”“one form,” or “an form” means that a particular feature, structure, orcharacteristic described in connection with the form is included in atleast one form. Thus, appearances of the phrases “in various forms,” “insome forms,” “in one form,” or “in an form” in places throughout thespecification are not necessarily all referring to the same form.Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more forms. Thus, theparticular features, structures, or characteristics illustrated ordescribed in connection with one form may be combined, in whole or inpart, with the features structures, or characteristics of one or moreother forms without limitation.

We claim:
 1. An ultrasonic surgical instrument, comprising: a handlehousing; a switch frame operably supported in the handle housing; and aswitch assembly coupled to the handle housing, wherein the switchassembly comprises: a first switch arrangement movably supported on adistal portion of the handle housing, wherein the first switcharrangement is selectively movable relative to a first switch contactsupported by the switch frame; and a second switch arrangement,comprising at least one of: a right switch button movably supported on aright side of the handle housing, wherein the right switch button isselectively movable relative to a right switch contact supported by theswitch frame; and a left switch button movably supported on a left sideof the handle housing, wherein the left switch button is selectivelymovable relative to a left switch contact supported by the switch frame;wherein the first and second switch arrangements are configured to beselectively actuatable by a single hand supporting the handle housing,wherein the right switch button is selectively actuatable from the rightside of the handle housing and is supported by a right switch arm thatextends laterally towards the left switch button, wherein the leftswitch button is selectively actuatable from the left side of the handlehousing and is supported by a left switch arm that extends laterallytowards the right switch button, wherein the right switch arm is pinnedto a left portion of the switch frame with a left actuation pin and theleft switch arm is pinned to a right portion of the switch frame with aright actuation pin, and wherein the right switch button is pivotableabout a right switch axis and the left switch button is pivotable abouta left switch axis.
 2. The ultrasonic surgical instrument of claim 1,further comprising a shaft extending distally from the handle housing,wherein the first switch arrangement comprises a first button assemblypivotable about a first switch axis, and wherein the first switch axisis substantially transverse to a longitudinal axis of the shaft.
 3. Theultrasonic surgical instrument of claim 2, wherein the right switch axisand left switch axis are substantially transverse the first switch axis.4. The ultrasonic surgical instrument of claim 1, wherein the leftswitch arm extends from the left switch button toward the right switchaxis; and wherein the ultrasonic surgical instrument further comprises aleft switch pin extending from the left switch arm, wherein the leftswitch pin is configured to contact the left switch contact.
 5. Theultrasonic surgical instrument of claim 4, wherein the right switch armextends from the right switch button towards the left switch axis; andwherein the ultrasonic surgical instrument further comprises a rightswitch pin extending from the right switch arm, wherein the right switchpin is configured to contact the right switch contact.
 6. The ultrasonicsurgical instrument of claim 5, wherein the left switch arm comprises ahole defined therein, and wherein the right switch pin is configured tocontact the right switch contact through the hole.
 7. The ultrasonicsurgical instrument of claim 5, wherein the right switch arm extendslaterally above and across the left switch arm.
 8. An ultrasonicsurgical instrument, comprising: a generator configured to generateultrasonic signals; a handle assembly, comprising: a handle housing; aswitch frame; and a switch assembly, comprising: a first switcharrangement movably supported on a distal portion of the handle housing,wherein the first switch arrangement is in electrical communication withthe generator and is selectively movable relative to a first switchcontact supported by the switch frame; and a second switch arrangement,comprising at least one of: a right switch button movably supported on aright side of the handle housing, wherein the right switch button is inelectrical communication with the generator and is selectively movablerelative to a right switch contact supported by the switch frame; and aleft switch button movably supported on a left side of the handlehousing, wherein the left switch button is in electrical communicationwith the generator and is selectively movable relative to a left switchcontact supported by the switch frame; wherein the first and secondswitch arrangements are configured to be selectively operated by asingle hand gripping the handle housing, wherein each of the rightswitch button and the left switch button are pivotally coupled to theswitch frame, wherein the right switch button is selectively actuatablefrom the right side of the handle housing and is supported by a rightswitch arm that extends laterally towards the left switch button,wherein the left switch button is selectively actuatable from the leftside of the handle housing and is supported by a left switch arm thatextends laterally towards the right switch button, wherein the rightswitch arm is pinned to a left portion of the switch frame with a leftactuation pin and the left switch arm is pinned to a right portion ofthe switch frame with a right actuation pin, and wherein the rightswitch button is pivotable about a right switch axis and the left switchbutton is pivotable about a left switch axis.
 9. The ultrasonic surgicalinstrument of claim 8, further comprising a shaft extending distallyfrom the handle housing, wherein the first switch arrangement comprisesa first button assembly pivotable about a first switch axis, and whereinthe first switch axis is substantially transverse to a longitudinal axisof the shaft.
 10. The ultrasonic surgical instrument of claim 9, whereinthe right switch axis and left switch axis are substantially transversethe first switch axis.
 11. The ultrasonic surgical instrument of claim8, wherein the left switch arm extends from the left switch buttontoward the right switch axis; and wherein the ultrasonic surgicalinstrument further comprises a left switch lug extending from the leftswitch arm, wherein the left switch lug is configured to contact theleft switch contact.
 12. The ultrasonic surgical instrument of claim 11,wherein the right switch arm extends from the right switch buttontowards the left switch axis; and wherein the ultrasonic surgicalinstrument further comprises a right switch lug extending from the rightswitch arm, wherein the right switch lug is configured to contact theright switch contact.
 13. The ultrasonic surgical instrument of claim12, wherein the left switch arm comprises an aperture defined therein,and wherein the right switch lug is configured to contact the rightswitch contact through the aperture.
 14. The ultrasonic surgicalinstrument of claim 12, wherein the right switch arm extends laterallyabove and across the left switch arm.
 15. An ultrasonic surgicalinstrument, comprising: a housing, comprising: a distal side; and afirst lateral side; and a second lateral side; a switch frame; and aswitch assembly, comprising: a distal switch arrangement movablysupported on the distal side of the housing, wherein the distal switcharrangement is selectively movable relative to a distal switch contact;and a lateral switch arrangement, comprising at least one of: a firstswitch button movably supported on the first lateral side of thehousing, wherein the first switch button is selectively movable relativeto a first switch contact supported by the switch frame, wherein thefirst switch button is pivotable about a first switch axis, and whereinthe first switch axis is closer to the second lateral side of thehousing than the first lateral side of the housing; and a second switchbutton movably supported on the second lateral side of the housing,wherein the second switch button is selectively movable relative to asecond switch contact supported by the switch frame, wherein the secondswitch button is pivotable about a second switch axis, and wherein thesecond switch axis is closer to the first lateral side of the housingthan the second lateral side of the housing.
 16. The ultrasonic surgicalinstrument of claim 15, further comprising a shaft extending from thedistal side of the housing, wherein the distal switch arrangementcomprises a distal button assembly pivotable about a distal switch axis,and wherein the distal switch axis is substantially transverse to alongitudinal axis defined by the shaft.
 17. The ultrasonic surgicalinstrument of claim 16, wherein the first switch axis and the secondswitch axis are substantially transverse the distal switch axis.
 18. Theultrasonic surgical instrument of claim 15, further comprising: a firstswitch arm extending from the first switch button toward the firstswitch axis; and a first switch pin extending from the first switch arm,wherein the first switch pin is configured to contact the first switchcontact.
 19. The ultrasonic surgical instrument of claim 18, furthercomprising a second switch arm extending from the second switch buttontoward the second switch axis; and a second switch pin extending fromthe second switch arm, wherein the second switch pin is configured tocontact the second switch contact.
 20. The ultrasonic surgicalinstrument of claim 19, wherein the first switch arm comprises a holedefined therein, and wherein the second switch pin is configured tocontact the second switch contact through the hole.